You can update your display language settings to set the display language for your Microsoft 365 websites. First, confirm that you can change your display language by going to the language settings on your My Account page (myaccount.microsoft.com/settingsandprivacy/language). If you're unable to change your display language there, follow the steps below to access your SharePoint online settings or contact your IT administrator.
Where do my SharePoint Online Language Settings Apply?
Your display language and region settings will be used for menus and buttons for the following web applications: Excel, Outlook, PowerPoint, SharePoint, and Word.
How to Access your SharePoint Online Language Settings
Go to Edit Details and click on the ellipses (…)
Select the Language and Region option from the drop-down menu.
In the Language Preferences section, Under My Display Languages, add a new language by selecting it from the drop-down menu and clicking Add.
If you have multiple preferred languages, use the up and down arrows next to the languages listed in the My Display Languages box to change their priority.
If you're not able to add or change the priority of your display language here, contact your IT administrator.
How Multiple Display Languages Work
If you have more than one language set as your display language, your applications will display menus and buttons in the topmost supported language. Make sure to order your display languages in your preferred viewing order.