1) make sure to disable "sync addons" in the curse client, otherwise youll magically see all your old addons appearing again.
2) make sure that when installing a new UI you have the correct folder structure ^^
so:
WTF > account > etc.
Interface > Addons > (a list with all addons)
the WTF and Interface folder go in the same directory as your launcher.exe and wow.exe are.
3) if you want to know wich wow folder curse is maintaining for you, look into the options/add game part to see which game is located where. What ive seen in curse, and i gotta love it ^^, is that when i copy my main wow folder to another spot, its auto-magically detected by curse again, showing me 2 different World Of Warcrafts in the list of games ^^.
if no addon button pops up in the character selection screen, double check if the addons are in the correct directory.
if an addon button pops up in the character select screen but you see no addons when you log in, make sure to enable "load out of date addons"
hope this helps
