when I change my usps address will senders be informed (credit cards, IRS) or do I have to do that?

You handle that. USPS would not have legal authority to release information, even if they could afford the staff.

USPS will forward your mail to the new address. They will also give you an information packet that helps organize notifying others of the change in address.

Provided that the sender requests notification, which you are going to become aware of on many of your credit card statements, personal loan or banking data. The envelop can have a message printed on it to thrill notify sender in the event of the tackle change. The sender can even be notified as soon as the forwarding order expires and the mail is back to sender.

Really the answer is both. Many vendors mark their remittances with "forwarding address requested." However it is first and foremost your obligation to notify those to whom you do business with of address changes. The USPS forwarding only lasts so long (6 months I believe).

My advice is to be forward on this. It is in your best interest for credit cards to get to you and only to you.