Squats are not the best exercise to target your glutes. Stiff-legged deadlifts, RDLs, barbell hip thrusts, glute drive machine, and glute kickback machine all target them much better.
If you want a glute-focused program, Bret Contreras is a widely respected, published doctor of sport science who specializes in glutes. He promotes the barbell hip thrust in particular for glute development.