I keep getting the "Something changed in your return, you'll need to choose your refund method again" when completing steps to apply for advance after preapproval?

Go back and run Review to see what has changed.

As @GeorgeDenseff mentioned, you can run Review to see what has changed. 

You may also want to try clearing out your browser's cache and cookies. Please see How do I delete cookies? and How to clear your cache for more information. 

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