PLEASE IGNORE - I just sorted it out:
Settings > General Settings > System > Start Screen > Resume Playback
Sorry if I wasted anyone's time!
I've been using Rockbox on my iriver H120 for about 5 years with no issues at all - until now!
My player always automatically resumed playback from the exact place it was when switched off, but this has just stopped happening. I did switch to a different theme, and it seemed to happen after that, but that shouldn't have caused this issue. I've tried upgrading to the latest 3.7.1 version and tried different themes, but no joy.
It's a bad one cos that 'one button to get it going' is a pretty key feature for me as I use it mostly in the car.
How can I reactivate the auto resume function?