YASNAC MX3 changing parameters

A few months ago got a Matsuura MC-510v with a Yasnac MX3 control. Had some initial issues but now it's running pretty solidly. The issue I now have is, because it has such limited memory I want to use some old programs that use sub-programs and the way it's set up is so that it recognizes M2, M30 and m99 as end of file. Parameter #6021, D0 is what changes it so it does not. I assume? that means it looks for the % sign like the Fanuc OM I had previously so I tried to change it but couldn't. I tried to change it by going to PRM and changing 6219 to 1 as instructed in the manual but had to go to SET instead and I'm still not allowed to change 6021. Anyone have an idea why not? When I first got the machine I has to reset the tool table so it was possible to change parameters at one point.
Since I reset the tool table I've had to change the rotary switch on the mainboard to reset the control but the rotary switch was turned back to the original zero position.
Also, I found a higher capacity memory card, does anyone know if the Memex instructions are correct for any size of memory upgrade?

Blowing off about an inch of dust and lots of cobwebs in my memory......

After you have SET 6219 to 1 you should be able to go to PRM 6021 and press the INSRT button then arrow down should move the cursor to the right. When it is under bit 0, press the WR button and it should change state. Press RESET and the cursor should move back to the address column. You may have to power down and back up for the change to be active.