RemNote does not have its own spell-checker – instead, it uses the spell-checker provided by your web browser (on the web app) or operating system (on the desktop app or mobile app). The language used by the spell-checker is thus determined by the settings in your browser or operating system.
For your web browser, you can usually tell the browser what languages you know and which you want it to spell-check. For example, in Google Chrome and other Chromium-based browsers, you can find the option under “Languages” in the settings.
(tip: you can quickly open Chrome's language settings by going to this address: chrome://settings/languages)
For your operating system, you can usually only configure one system language, and this will also control the language that interface text appears in. The details will depend on which operating system you're using. (If this makes using the desktop app a pain, you could consider using the web app instead.)
If you're unable to set your browser or operating system language to match the language you're taking notes in, for whatever reason, and you'd prefer having the spell-checker turned off to having it check your notes in the wrong language, you can disable it in Settings > Editor > General.
How to add or edit the Spellcheck languages on the Desktop App
Although it is not as simple, there is a workaround to edit the Spellcheck languages on the Desktop App. You will need to edit the app's "Preferences" file to add the spell-check languages you want.
Here is how to do that on Windows:
1. Make sure that RemNote is fully closed.
2. Go to the RemNote's AppData folder, which is located in C:\users\username\AppData\Roaming\RemNote
Note: instead of "username" you will see your system's username.
Note: if you don't see the AppData folder, try enabling the "show hidden folders" option on your file explorer.
3. There, open a file called Preferences with a text editor.
4. At the end of the file, you should see a text like this: "spellcheck":{"dictionaries":["en-US"],"dictionary":""}} . There, you can add the languages you want to have the spell check for by adding its Locale ID.
For example, to add French to the list, add "fr" after "en-US". The end of your file should look like this: "spellcheck":{"dictionaries":["en-US","fr"],"dictionary":""}.
You can search for the ID of your language in this link.
5. Save the file and close your text editor.
Done! Now your RemNote App will have spellcheck enabled for all the languages you added to that list.