A while ago I got this dialog and checked the "remember my decision" checkbox like this:
I clicked "Yes" and it remembered that but now I don't want to open the Flex Debugging perspective when it suspends. However I no longer get this dialog and thus the option to change my decision. Flex Builder prefs/help is terrible how do I change this now?
From the top menu, select
In the [Debug] Dropdpwn option, select None. Click OK. Switch your perspective to Flex Development. You will get the prompt when you debug.