I don't understand why some MODs don't work after style change
 

Running 3.8.X and testing some styles and there are some very simple MODS that don't work in those styles...

What is the most common thing I am suppose to do or check for to get a MOD to work in each style?

Don't styles all share the same templates as the 'edited/modded' DEFAULT style or did they load default templates and I got to edit them again??

Or do I go back and install the MOD into the new style again?

If you've changed anything in any child style template a modification in the parent style will not affect it. You'll have to go through all the child style templates and revert any of them shown in red. You will lose any special changes in the child style though.

Some mods use search/replace to add their code into the templates. If the template is modified and that code has changed, then the search/replace won't work and so the modification code won't be added into the template.

THNX Lynne, but then there really is nothing to do?
OR, can I take the new style I want to keep and make it the only style and then reinstall some of the MODs?
I guess it's not a huge deal but I have a few cool tweaks that are not in effect in the style I really want to use... They still work and show up in the DEFAULT style, but not in the new one I loaded.

Do the tweaks manually. Read the plugin code and just take the html out and manually add it to the template.