I had an unusual question today.
There was an account form which had four different forms, one of the forms had unticked
Show navigation items
I didn’t even know this option existed.
What was happening was the form had the Show navigation items unticked, so when you went to the form it had no navigation items. The problem this brought up was it was then impossible to change back to any previous forms because the form picker was on the navigation pane!!
You can setup the different forms to display to different security roles but if you would like users to choose which form they want to use or if a number of forms available you have a form picker available.
CRM helpfully remembers what form you used last and then uses that form the next time you view that entity, so we were in the situation of not being able to change forms once you had viewed the form with no navigation pane.
The way I got round it was to enable the navigation pane and personally I don’t think you would really want to disable it.