I have to assume your pots are all stainless steel and don't have a Teflon type of coating on them.
Use a Brillo or S.O.S pad and scouring powder. You might want to try soaking the pot with powdered Dishwasher soap before you start and heating water in it is a very good idea... Then scrub, scrub and scrub... might even need to use a few steel wool pads. If you have a dishwasher, after you've scrubbed the pot almost clean, more of the burned area will come off in the dishwasher. It might take you a few times scrubbing the pot, using it, scrubbing again, using it, but it will get clean.. I also find that if I heat my pot with a solution of my hand made soap, for some reason the burned comes off easier... but could be I'm not burning them like I use to either.
I use to do a lot of entertaining and those pots got a good work-out! Stains that I never thought would ever come off, did and after 30+ years, they still look almost new, including the one that stuck to the electric burner, it was that bad, though I have to admit, the pot did warp a little :shrug: