Fix issues with multiple Google accounts
Users with multiple Google accounts signed in at once  on a browser may experience issues  while using the add-on. To fix issues from multi-login, try one of the following solutions:
Open your browser in private/incognito mode.
Sign out of all your Google accounts and only sign in to the one that has Budget n Sheets authorized.
"Sign in to multiple accounts at once", Google Account Help
"Fix issues with multiple Google Accounts", Google Apps Script