Yes, that's possible.
You can selectively enable *back
in parts of your program by turning the setting on and off.
For example, add
*settings
*back: yes
*menu: no
before sections where you want users to be able to go back. In sections where you no longer want users to do that, add
*settings
*back: no
*menu: no
This is useful in several settings. For example, you could allow users to go back while answering screening questions up to the point where their screen-in / screen-out status is determined. You likely wouldn't want a user who screened out to return and answer differently.