Changing the language of your Studio CMS is something you wish to do. Once you do it, the Studio will “remember” your new default every time you login to your Studio account.
At the moment the Monitoring & Reports tool is not multi lingual yet, but in the future it will be. The Admin tool (for partners only) is also multi lingual (the default language will be taken from the chosen language of the managing user).
In order to choose a different language, just login to your Studio account with your credentials (user and password) or by Google/Gmail SSO (see this article for how to login).
Once you’re in, click the flag icon in the top right corner and choose the language of your choice.