Where are my files? I can never find them via GMAIL or My Files on my Samsung

The problem is I'll download a PDF, open it in acrobat and fill it out. Then I'll save it and want to send it via Gmail.

The thing is, I can never find it anywhere besides Acrobat. When I'm in Gmail and click attach files I can't find the document, or acrobat for that matter, in anyway.

When I search through my docs straight from the home screen, same issue.

What am I missing here. Are the files only ever in Acrobat? When I'm on the app they have a little cellphone under the PDFs title but they're unfindable.

I work gigs and can get a new job every couple of weeks so I like to knock it out on my phone and I'm just tired of playing weird games to get my multiple PDFs from acrobat into 1 Gmail.

Help please?

Samsung S21