I tried to use the 'preferences' from one of my alts in order to save time setting it up again

[Rolig Loon]

It sounds like you scrambled one of the hidden files for your viewer by trying to copy data for one account into files meant for another one.  There may be a clever way to do that, but at this point you will probably have to start over again by doing a clean re-install of the viewer and re-entering your Preferences for both accounts. 

[Rolig Loon]

It sounds like you scrambled one of the hidden files for your viewer by trying to copy data for one account into files meant for another one.  There may be a clever way to do that, but at this point you will probably have to start over again by doing a clean re-install of the viewer and re-entering your Preferences for both accounts. 

[CassieMaia]

I agree with Rolig that at this point you need to do a clean install of the viewer and then set your preferences again.

One thing to keep in mind for the future is that there are alot of preferences that are 'viewer' specific and not 'avatar' specific, so when you create an alt and login in with the alt on the viewer you usually use, most of the preferences will already be as you had set them previously.  It's just a small number of preferences that are avatar account specific.