Thank you page edit option has disappeared from my form

The thank you page editing option has dissappeared from my screen?

This screenshot corresponds to that of a Card form.

For Card forms, the Thank you page edit option is at the bottom of the Form Builder itself. 

Scroll down to the bottom of your Form Builder and at the end of the last card, you can see "Edit Thank you page" button.

Here is an example:

If you are facing any further difficulties, please let us know.