Aura: Full Screen Reading setting lost

I've got an Aura running 3.80. I had a problem earlier and had to do a restart. Since then i've lost the section in Reading Settings to turn off header and footer (I'm sure i had a check box there)

I've had a look at the Config File and its nothing like I remember (I have a copy of 3.3's) and I have no section titled Feature Settings any more so I have no idea where to insert

FullScreenReading=true

Can anyone advise? :thanks:

Edited to say that if i open my config file in Notepad ++ I have 45 lines now, compared to 202 lines in 3.30