I had gall bladder surgery a month ago. My belly button was an innie but is now an outie. When will it go back to normal? Can I do something to help?

Not sure. If you had the "outie" directly after surgery, it may be how the surgeon put the incision back together, and the only way to fix it is another surgery (only needed for cosmetic reasons). If it was an "innie" after surgery, but all of a sudden is an "outie", then you may have a hernia related to the surgery.
See your surgeon. This may be due to normal swelling due to the proliferative wound healing phase, and often referred to as a "healing ridge". Could also be that the attachment of the belly button was lifted off the abdominal wall during surgery. Lastly, it could represent an opening of the abdominal wall, also known as a hernia. See your surgeon for an exam, and specify your goals for an outcome.
Go see the surgeon. It could be normal postoffice changes but if it does not change in another 2-4 weeks, you should see your surgeon; it may be a hernia.