Unable to choose account to share docs from Started using this new Samsung S9 a week or so ago and it has an annoying trait/bug in Gmail that my older S6 Edge/S5 never had.

If I choose a document or photo, from any app, to share, the system always choose the same e-mail account and the drop-down menu for my other two accounts is inactive. However, if I use any of these accounts via Gmail first, the drop-down menus appear, showing all three Gmail accounts. I can't figure this out.

Any ideas? The latest update didn't sort it either.
Right, for some unknown reason (no obvious updates, either) the drop-down email addressed are now visible when sharing from an app itself! Weird!

Sorted!