I have several different ringtones and text message tones downloaded into my phone. I have no problem setting ringtones, however I cannot change my text message tone to anything other than the factory tones that came in the phone. I will change them and the phone will show them as the set tone, but when I receive a text a generic tone is heard. Any suggestions?

If it lets you choose them, they should play... Have you gone back to settings to see if they changed by themselves? How long are the tones? You might try an extremely short to to see if that works. Sometimes tones that are too big won't work.

This used to be a known problem: http://www.lgcommunity.com/forums/aff/9/aft/5548/afv/topic.aspx
I have not heard if this is fixed. I am still running the same T84UCV05.
Watch out for firmware updates: http://www.lgcommunity.com/forums/aff/10/aft/5889/afv/topic.aspx