I mean the amp reading withing the screen, its 0 when no use, but when I push the fire button and waiting for a tiny bit, it stays at 20.3 or 20.4
Also, danm this is all so complicated.
That might also be 20.3 or 20.4 Watts you see on the screen.
I think you ought to be fine holding your fire. Sorry, lemme translate that for you. Holding your fire means to keep on keeping on as you are doing. If it's wattage being put on the screen you're alright. It is usually good to start out with low wattage and gradually move up. Wattage is also called Power. This means the "work" the electricity can do, in this case it's heating the coil/s in your atomizer.
Here these might help.
Volts are what your battery/ies have, the contained electrical energy. You push the fire button which closes the circuit, opens the flow of Current/Amps. Amps then get turned into Power/Watts by doing the work, in this case warming up the coil. The Resistance is how the wire coil is formed to impede the Watts from doing their work, creating heat, and in impeding this creates the Watts doing the work. At the one end of the coil is a positive lead. The other end is the negative or Ground lead. Current flows through the coil to do the work, become Watts.
I agree it is a lot of complexity at first. Still mess up at times myself. I don't care much for math but can do trigonometry if I get tricked into doing it. This, this is simple algebra, although it doesn't seem like a walk in the park I'm sure. Regulated mods, ones having screens, bells & whistles usually handle being a calculator for you and you can go on and vape away until you get a battery low warning. When you start with mechs you have to kind of trail and error find a safe zone to build coils congruent to battery specs, more so. This is why, with you using a regulated I'd suggest you hold your fire. You're doing alright for what you're doing.
But yes, do study the images above, download them to use later when you need to recall it. You'll eventually be laughing at your regulated for reading the ohms wrong on a coil once you get the math down. Hope I'm helping.