Backup Form Before Modifying

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You can easily copy a form with one click. When you go to your list of forms, even if it is just one form on the list there's an icon over to the right. You can have many Forms as you like. so before you do anything you might regret just make a copy of the form, and name it appropriately. 

In addition, as soon as you have more than one form in a table a new section opens up in the forms management area  to control forms usage.  That allows you to specify which forms get used either as the default form or you can kind of go crazy with different forms for different roles in different forms for different reports.

So bottom line, just make a copy of the form before you make significant changes and then if you need to you can simply roll back to using a previous saved form by changing the default Form in Forms Usage.