open acount eg credit card that is not based on a written co

How can a credit card account that is a revolving open account not be based upon a written contract? All ofv the terms of the agreement are in the application so when one signs the application it is considered as a written contract. But can anyone be creative and tell me I'm wrong that one has signed a contract and that lawyers and courts do not separate open account from the contract one has signed so that in Florida, they look at the SOL of a signed contract rather than the SOL of an open account???