I do not use microsoft but there is an M at the bottom of my home screen so try that.
A person could save a file and move it or put it in email I would think.
Control J is a way to quick access a pdf file I just learned last week.
What I did was just try to do one new thing a day with it and in a month I had learned a lot.
try typing in your search bar / Microsoft 365/ see if you can get to a login screen
or how to access microsoft 365... in search bar.
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It is not the M that is for mail. LOL!
I do not know on the external device.
Type that in your search bar how do I save to external .....
found this .....
How do I save files to an external hard drive on a Chromebook?
Transfer Files to a USB Drive or Memory Card on Google Chromebook
Connect the drive to Chromebook.
Click the icon. Click the Files. ...
Select files and folders.
Drag and Drop or Copy and Paste the files from the drive to Chromebook. ...
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/ walked the ddoggo