What if someone put you on the credit card account and said you could use the credit card am i also responsilbe for paying the credit card bill?

In general, NO!

If you did not sign anything to be a member then you are not bound contractually, period!

However, discover has sued people who were put on as authorized uses and then you have to sue back or provide proof that you were just a non-binding card carryer. So they can hold you resposible, but not legally - you may have to fight to get off the account.

BoA allows primary card members to simply enter a name, birthdate, and social security number for an authorized user and then they begin REPORTING to the credit agencies that primary person's credit card activity. So, this can be used to suddenly make it seem like you have a credit card and good credit when you really do not - this is a common technique used by gurus to instantly build credit. But, it will also show up as a defaulted account if the main card member defaults! So if this happens, you will have to all in and claim that you are not the primary card member and have them quit reporting to you (you might also deny that you ever gave permission to be an authorized user!)