I got another PC for my cnc and Mach3 doesn't remember the last tool position when I start the software the next day. My old PC didn't do that.
Sometimes I'm forgetting to Zero the axis and when something goes wrong, like loosing steps, I loose my zero.
I can`t find anything about it in settings.

And is it normal that I can`t jog with 3 axis at the same time? Sometimes I can, but usually just 2. I did try with 2 different PCs.

General Config page has options for making DROs persistent.
As for Jogging then you should be able to jog all 3 at the same time assuming you have not come against a soft limit on an axis.
Hood