Another option if you find your e-mail client has somehow gone into bottom posting mode is to make a point of deleting the entire quoted content (CTRL+A followed by either Backspace or Delete) before typing anything at all.
This is actually an excellent practice even when top posting is active when the quoted material is not really necessary.
Brian - Windows 10 Pro, 64-Bit, Version 1809, Build 17763
Puritanism: The haunting fear that someone, somewhere, may be happy.
~ H.L. Mencken