Recommended answers to the "stay signed in to all your apps" question for Office 365:
When you connect to or interact with Microsoft office 365 in some way using your PC or laptop, such as when you setup your mail in Outlook, you will often get the popup below asking you if you want to "remember your account". While this may seem like a reasonable idea, unless you explicitly know what this is will do and want that to happen I strongly suggest you chose "no, sign in to this app only".
This will avoid some potentially undesirable consequences such as "binding" your PC to your organisations Azure active directly security for administration, setting up for you files *not* to be saved to your PC or network share by default, but instead being saved to your organisations online "SharePoint" server. If this happens by accident these and some other consequences will need to be reversed, sorted out, and things put back where they belong.
This is also why I also recommend that all PC's are initially installed as standalone PC's with a local administrator account.
If you're a digitalwelcomemat customer, your organisations centralised security and file store won't be Microsoft Azure or SharePoint so there is no advantage to using this Microsoft "feature".