After you file

For On-Line version
You appear to be using the TTax On-Line version.  Unfortunately the on-line version does not support a 'what-if' scenario (that is only available with the desktop version).

Once you make ANY changes to the online version the previous information is overwritten and is PERMANENTLY deleted.  You will have to manually re-enter/re-create your return.

You might want to try to create NEW dummy accounts for your various scenarios and then simply abandon them when you are finished.

Create New On-Line account:
turbotax.com and look for the 'New to TurboTax?" 'Start for Free' BLUE button near the top center of the screen.