Is there an easy fix to ensure the device returns to manual mode sooner while leaving the 7 second "hold" of a random scene?
I am always unsure whether to gve the quick answer, or just to tell about the approach as it (usually) is fu working it out yourself.
So the "hint" this time is - the much famed and abused "blink with out delay" - because you must not use delay if you want to do
two things at once. (in this case, (1)monitor the pot value and (2)count to 7 seconds before doing another random)
I tried to give an alternate explanation -
http://arduino.cc/playground/Code/AvoidDelay - see if it helps you. If not, I'll just write the 5 lines of code you need.