Before you are attempting to change the scope back to the smaller sequence, make sure that the cursor/control/selected activity on canvas is on the smaller scope sequence , the dropdown the the scope you see on the variable panel shows the scope based on the current sequence activated in canvas.
If the control is on outmost sequence it just shows outmost scope.
if control is on the inmost sequence, it will show all the scope
Hope it helps.
Thanks and Regards
Rishabh Pandey