I posted because I had not heard from PM after a few days. Just in from PM:
The arrows are for a special-use function that may not be all that useful. It's used with the zero key as below:
"Zero ----- reset / preset function key. The digital display ruler can realize zero clearing at any position. When the preset function is needed, long press the zero key for more than 3 seconds, and when the "s" flashing symbol appears at the top right of the screen, you can set the value you need through the preset number setting key. After setting, short press the zero key, and the "s" flashing symbol disappears, and relative measurement can be carried out."
The arrows are the "preset number setting key" that they talk about. never tried using it!
I don't know what to do about the cover. I would guess it will be less stiff as it "breaks in"... I guess you could train it to fold properly by restraining it with a loop of string in one or more places, but they may not slide up and down the column well. Leaving the head down to fold the pleats when you're not using it could help too.