I'm not sure if there is an easier way, but I used this method to change account associated with the YouTube app on my DROID.
1. I logged in to the PC and changed the password for the google account associated with my YouTube account. (If you aren't using a google account with your YouTube account, I suppose you could just change the password for your YouTube account).
2. I went into the YouTube app on the DROID, and of course it now says it has a problem with your YouTube account.
3. On your DROID, go through the motions of uploading a new video. It will prompt you for a username/password.
4. Enter the new username/password, and now your YouTube app will be associated with the new YouTube account.
Again, there may be an easier way, but this is the only way I could figure out.
1. I logged in to the PC and changed the password for the google account associated with my YouTube account. (If you aren't using a google account with your YouTube account, I suppose you could just change the password for your YouTube account).
2. I went into the YouTube app on the DROID, and of course it now says it has a problem with your YouTube account.
3. On your DROID, go through the motions of uploading a new video. It will prompt you for a username/password.
4. Enter the new username/password, and now your YouTube app will be associated with the new YouTube account.
Again, there may be an easier way, but this is the only way I could figure out.