I use an MX-A which, from my understanding, has the same menu interface as the MX-3.

The bad news: There's no stopping the flashing. Sorry. I just try to ignore it. You could always just put a piece of duct tape over it I guess.

The good news: The memory is non-volatile, which means that you won't lose your settings when you change your batteries. However, I haven't tested whether or not leaving out the batteries for a long time will clear the memory (as in some digital cameras).

I hope this helps.