Gain and Crossover Level

I want to know how should the amp gains be set when a crossover is present, and how should the crossover levels be set.I have an Alpine CDA-7863 headunit,an Autotek ATK2/3 way crossover, And I have a Autotek SX275 on the rears, a Alpine V12 MRV-T302 on the fronts and a Alpine V12 MRV-1505 on the subs. They are active crossovers.

What DYohn told you in your previous thread.  You have more crossovers than you need, so you have to choose which one to use for each bandwidth and bypass the others.  Set your amp gains using a multimeter with all components installed in the signal path.  You will have to go back and recheck the gains after adjusting the crossovers that you decide to use.  You can find info with a search of this forum, if you need to, on how to figure out voltage output using Ohm's Law... and whatever else is necessary for setting gains by meter.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.