Select a payment method to view or edit its details.
Update the payment method information.
When you have made your changes, select SaveandClose.
On the other hand, moving your company file from one location to another will not take you at most 24 hrs. During the process, yes can't use your books.
You need not to worry though, there's an easy and faster way to do it. Just make sure to create a back up the old company file then restore it to the new computer. This way, your file is protected from accidental data loss.
However, if you're referring to transferring the ownership of the company to new owners, it will take 24-48 hrs for the approval. Yes, as long as you have the access to your QuickBooks you can still work with it.
Keep me posted if you have other questions. I'm always here to help.