You ask in Chinese (say, “summarize Apple’s latest earnings”) and Gemini answers in English; or you type English and get Chinese back. Gemini decides the reply language from several signals at once: the language of your prompt, your Google Account language, your browser’s Accept-Language header, and any attached document. When those signals conflict, it does not always pick the one you meant.
Fastest fix (works for that conversation): put a one-line instruction at the very start of your prompt, then your question:
Reply in Chinese.
Summarize Apple's latest earnings.A leading “Reply in X” overrides every other signal for the current chat. To make the right language stick across every new chat, align your account language and browser language too (steps below).
This is a behavior of how Gemini weighs language signals, not an outage. Verified against the Gemini Apps “Change Gemini’s language” help page as of June 2026, running Gemini 3.1 Pro.
Which bucket are you in?
| Symptom | Most likely cause | Go to |
|---|---|---|
| Every chat defaults to the wrong language, even fresh ones | Google Account language ≠ your language | Step 2 |
| Wrong language only on gemini.google.com in the browser | Browser Accept-Language ≠ your language (web has no in-app language setting) | Step 3 |
| You wrote your prompt mixing two scripts in one sentence | Mixed-language prompt, model leans English | Step 4 |
| Wrong language only when summarizing a file or pasted text | Gemini inherits the document’s language | Step 5 |
| One specific reply came back wrong | One-off signal collision | Step 1 or Step 6 |
| Want it permanent without retyping every time | No persistent language instruction saved | Step 7 |
Common causes, by frequency
1. Account language differs from your prompt language (most common)
Your Google Account language at myaccount.google.com/language is Gemini’s baseline assumption. A Chinese speaker whose account language is English will get English replies by default.
Check: open myaccount.google.com/language and read the language under “Preferred language.”
2. Browser locale mismatch (web only)
The Gemini web app at gemini.google.com has no separate in-app “Display language” setting — as of June 2026 it follows your browser/device language. Gemini reads your browser’s Accept-Language HTTP header, so a Chrome language that differs from your account language nudges the output.
Check: open chrome://settings/languages and read the top language in the list.
3. Mixed-language prompt
A single sentence that splices two scripts inline (Chinese characters with English verbs and nouns dropped in the middle) confuses the model, and it tends to fall back to English because that is where most of its training data sits.
Check: is your request one sentence written in two scripts at once?
4. English document, you want a non-English answer
Ask Gemini to summarize an English PDF and, unless you say otherwise, it inherits the document’s language and answers in English.
Check: is the attachment or pasted content in a different language from the one you want back?
5. No saved language preference
If you never told Gemini a persistent preference, it has nothing to lean on and falls back to account and browser signals every new chat.
Step-by-step fixes
Step 1: Lead the prompt with the language (instant, per chat)
Most reliable, and it needs zero settings changes:
Reply in Chinese.
[your actual question]Other phrasings that work:
Please reply in Chinese: [your question][your question]
(Answer in Chinese only.)Putting “Reply in X” at the start beats putting it at the end. Per Google’s help page, a prompt can set the reply language for that conversation with no account or app setting changed.
Step 2: Set your Google Account language (the durable fix)
This changes the default for every new Gemini chat and every Google product:
1. Open myaccount.google.com/language
2. Click the pencil/Edit icon next to "Preferred language"
3. Search for and select your target language (e.g. Chinese (Simplified))
4. Click Select
5. Close and reopen the browser tab, or refresh gemini.google.comSome surfaces take a minute or two to pick up the change. You can also click ”+ Add another language” if you read more than one; the top one wins.
Step 3: Align the browser language (web)
Because gemini.google.com has no in-app language toggle, the browser setting is your lever on the web:
Chrome → chrome://settings/languages
Drag your target language to the top of the list
(Optionally enable "Display Google Chrome in this language")
Restart ChromeThis sends the correct Accept-Language header. On the mobile apps there is an in-app control instead: tap your profile picture, then Settings → Languages, and pick your language (note this mainly governs menus, notifications, and voice input rather than the reply text — the prompt instruction in Step 1 is still the lever for reply language).
Step 4: One language per prompt; quote foreign terms
- Avoid: a single sentence in your target language with English verbs and nouns spliced inline (e.g. asking in Chinese but with “summarize” and “this article about AI” embedded mid-sentence). That mixing pushes Gemini toward English.
- Do: write the whole request in one language. Want Chinese output? Write the entire prompt in Chinese. Want English? Write it all in English.
When you must reference a foreign term, put it in quotes and keep the rest in your target language:
Summarize the paper titled "Attention Is All You Need" and reply in Chinese.The quoted term stays foreign; the base language stays primary.
Step 5: English doc, want a non-English summary — say so
Gemini inherits a document’s language by default, so override it explicitly:
This PDF is in English. Summarize it in Chinese.Or write the whole instruction in your target output language so the request and the desired reply share one script. Either works; being explicit is what matters.
Step 6: Correct it mid-conversation
If a reply lands in the wrong language, answer with a one-line correction in the language you want:
Answer the previous question again, in Chinese.Gemini switches and generally stays in that language for the rest of the chat.
Step 7: Save a persistent language instruction (cross-session)
Use Personal Intelligence (Google’s personalization layer, rolled out to Gemini in early 2026) so you never retype the preference:
Web: Menu → Settings & help → Personal Intelligence → Instructions for Gemini
Mobile: Profile picture → Personal Intelligence → Instructions for GeminiAdd an instruction such as:
Always reply in Chinese unless I switch to English explicitly.This applies to new chats across devices. Note it does not apply inside Gems or Live chats, and it needs a personal Google Account. See the Gemini personalization help for current availability.
How to confirm it’s fixed
- Start a brand-new chat (don’t reuse the one that misbehaved — old chats keep their language momentum).
- Type a neutral prompt with no language instruction, e.g. just your question.
- If it replies in the right language with no “Reply in X” prefix, your account/browser/saved-info signals are now aligned.
- If it still drifts, fall back to leading every prompt with “Reply in X” (Step 1) — that always wins.
Prevention
- Save “Always reply in Chinese unless asked otherwise” in Personal Intelligence → Instructions for Gemini.
- Keep account language and browser language consistent so the signals stop conflicting.
- Lead prompts with “Reply in X” rather than ending with it.
- One language per prompt; quote foreign terms instead of inlining them.
- For foreign-language documents, state the output language you want.
FAQ
Why does Gemini keep ignoring my account language and answering in English? English dominates Gemini’s training data, so when signals are weak or conflicting it leans English. A leading “Reply in X” instruction (Step 1) outranks the account default for that chat; for new chats, fix the account language (Step 2).
Is there a setting to permanently lock Gemini’s reply language? Not a hard lock, but close. Set your Google Account language (Step 2) and add a persistent instruction in Personal Intelligence → Instructions for Gemini (Step 7). New chats will then default to that language without a prompt prefix.
Where is the language setting on gemini.google.com (web)?
There isn’t one inside the web app as of June 2026. The web app follows your browser/device language, so change it at chrome://settings/languages or in your Google Account at myaccount.google.com/language. Only the mobile apps have an in-app Settings → Languages control.
I changed my account language but Gemini still replies in the old one. Why? Existing chats keep their language. Start a fresh chat, and refresh or reopen gemini.google.com so the new setting loads. Changes can take a minute or two to propagate across Google surfaces.
Why does summarizing an English PDF give me an English answer even though I asked in Chinese? Gemini inherits the document’s language unless told otherwise. Add an explicit line like “Summarize it in Chinese” (Step 5).
Does mixing English words into a Chinese prompt really change the output language? Yes. A sentence that mixes scripts inline biases Gemini toward English. Write the prompt in one language and quote any unavoidable foreign terms (Step 4).
Related
Tags: #Gemini #Debug #Troubleshooting