I bought a new MTB recently that came with TEKTRO HD-275 hydraulic disk brakes, after two weeks it has started to squeal, then I clean both front and back pads with Isopropyl alcohol and 120 sandpaper, now back wheel squeal is okay, but the front wheel squeal is still there?

What should I do? Replace front pads with new, or again clean with Water + Isopropyl alcohol + Rub more with Sand Paper?