Need help setting crossovers

I just picked up my truck with my new system in it. Audio guy was in a bit of a rush so don’t know if everything is set correctly and kind of want to learn this stuff myself (and most of all not blow anything). I have morel tempo ultra mk2 front and rear speakers and tweeters. Two 12 inch jltw3’s and an alpine ilx f511 head unit.

They’re running on a jl 400/4 and a jl rd1000/1. I know he set gains correctly for both but not sure what to do about crossovers. I looked at the amps and my 400/4 is set to full range and the 1000/1 is set to 80 lpf.

I’m assuming after using ChatGPT that since my speakers amp is set to full range I want to set a hpf on my head unit at 80hz and 24db slope for the front speakers. I also set the rear speakers to 100hz and a 24db slope.

Now what I’m confused about is the subs lpf in the head unit. Since I don’t have an option to set it to 0 on the amp should I just leave that at 80hz and keep the lpf off on the head unit? I was reading that having both will make them overlap and give you a 48db slope instead of 24. I don’t know how accurate this is and any suggestions would be greatly appreciated. Was a lot of money spent and don’t wanna blow anything