You don't want to install an older version, as it leaves you vulnerable to many security issues. If you'd like though, you can tell us what problems you are having with 19 and we can help.

When I type letters, numbers appear. The problem is occurring intermittently. I thought I had it solved when I disabled 3 add-ons that I downloaded today after updating to Firefox 19. Typing was normal for a while and then the problem returned. I was able to type this note by doing it in word, copying and pasting it into the browser message box.