Our company is using MS Office 365. To use that one needs to be logged into Office (via the company's login-page).

Now I would like to be logged into a different account for a specific application (OneNote), because I keep my notes under a different user (an MS account).



Is that possible at all? When I try to log into a different account in OneNote it keeps telling me "Can't sign in with a Microsoft account - This program is blocked by group policy editor...". :-(

Why is that so and is that possible somehow, nevertheless? Why can't I be signed into different accounts in different applications?

Group policy editor means your IT department.

(Assuming that the error message is relevant and not random.)
That would mean that your IT department has blocked using any other account on their equipment.