Cattitude

I think I must be missing something for tension adjustment on this machine. For most quilts I try to use the same colour thread in top and bottom but really don’t want to on this quilt. Top thread would be grey, bottom purple. Both 50wt, same mfg and style thread. I have tried every tension setting on the machine and nothing works. In order to be clear of purple thread on the top I am on tension 3....and the back is not looking good. I have tried every possible speed on the machine, doesn’t make a difference. I see mention at times of bobbin tension adjustments....is this only on long arm machines? Any suggestions would be welcome.