Somehow my PC selected Adobe Reader as my default 7-Zip reader and I can't figure out how to change it. How do I change the default reader and what are good choices to select for a 7-Zip reader?
What do you mean by reader? Do you mean that if you select View on an archive in 7-Zip, it will load Adobe Reader?
If so, it's easy to fix: in 7-Zip, go to Tools menu -> Options... -> Editor tab -> click on the ... button next to the View field and choose a text editor. By default (when the field is blank) it's supposed to be using Notepad but evidently some extensions must has screwed up. I use Notepad++ myself but you can choose anything really.