I looked at the documentation, and I can't find anything on changing the timeout period for scanning. I would recommend you call Support at 1-800-821-2797 to speak with a specialist on your device.
I just wasted another half hour of my life on this poorly designed interface. After scanning 15 pages of carefully lined up photos, I was given about a half second warning before the scanner timed out and aborted my 15 jpegs in 8.5x14. In my previous attempt, I used the preview structure before it timed out and lost everything. Aha! I thought, this time I'll outsmart the printer and do individual scans. But then, in the process, it allowed me to add more, and I naively thought "Oh, this is even better. I won't have to set up from scratch using my preset each time."
I'll admit just a bit of frustration when the add a page on-screen button was scant millimeters from the cancel button, but I paid close attention and avoided the cancel button successfully every time. Until the device OS snuck up behind me and timed out, losing my carefully invested time yet once again.
I think I give up. There is no way that I can see to use this printer to benefit. Sure, if you're scanning whole sheets, I'll bet it works. But that's not what I'm doing. I'm individually placing 6-10 old family photos on the glass, separating them slightly so photoshop automation will pull them as individual photos. That interface works. But not really I guess, if this printer refuses to allow me to scan them in the first place.
I looked through the interface several times to see where the timeout settings would be. But alas, they don't exist in a way that I can discover anyway. So my old paper photos will remain paper. Maybe I'll invest in a real scanner.
Ron in Maui