Can anyone explain this random Outlook / file sharing wierdness?

[BrightOrangeDahlias]

Hi, hoping there's someone out there who can explain what's going on and allay my concerns. I'll try to add enough detail so people can diagnose the issue, so apologies if it's too much!

Ok, the question: I help run a hobby group, and we have an outlook account which we use for the admin side of things. Three of us have access to it, and we use it for emails and for storing files in Onedrive. This evening I logged onto my personal laptop and was using Excel. As I went to open a file, on the list of "recent files" was a file that clearly belonged to another Hobby Helper's husband (the file name was a total giveaway). I've previously noticed files appearing that seemed to belong to the other Hobby Helper, again due to the file names, but didn't think anything of it. But tonight's file gave the path as a sharepoint site belonging to the husband's workplace. I didn't click on it as I didn't want to access something I shouldn't, so I don't know if it would have opened or not.

But it's got me worried - are my files appearing on their laptops too? What's going on?!?

I'm logged into google on my laptop, and also into outlook with my personal account and sometimes switch to the hobby outlook account when I need to.

Can anyone advise?

I think it's because the excel being uses is associated with that account. Excel these days is a licence, so if you are logged into a particular account when you use excel the file is associated with that account regardless of where it's saved.

I hate it.

So any file I open in excel while I'm logged into Hobby Outlook is accessible to anyone with access to Hobby Outlook?

Hang on, I'm now linking this to another "issue". If I'm on my work laptop, my company's security settings prevent me from logging into Hobby Outlook. (I get an error message about access to external file sharing sites being blocked or something similar). However... if I open, say, PowerPoint, I can often see hobby files that I've been working on on my home laptop. They open, I can edit them and save them again... even though I've never actually logged into Hobby Outlook on my work laptop because work have banned it!

I think you can open any files that you have on your computer, but once you have saved them again they will be associated with your work powerpoint and then they will be visible by someone using the work account (but work should have one account per person, so that person should only be you).

It's an issue when people are sharing accounts, which microsoft would argue they shouldn't do, so they won't bother to fix it.

That's really weird. Do you log into your work Outlook account on your personal laptop? Do you log into either on your phone?

No to both. It's technically possible to log into my work account from my home laptop but I've never done it. And I have a separate work phone so I've never used my personal one for anything work-related.

I've just gone into PowerPoint on my work laptop this morning and there are another set of hobby presentations appearing in my "recommended for you" ribbon on the PowerPoint landing page.

I'm not so worried about the hobby stuff appearing on my work computer (apart from the optics of opening up an Office program in front of colleagues and having something hobby-related glaring at them!). My main worry is the random personal files (like my friend's husband's stuff) popping up on their computers. Not that I'm up to anything dodgy, but I don't want my period tracking spreadsheet or my tax return calculations being widely viewed!