No matter what I set my cool for 70 and it stays at 78

While filter is out checking the coil check filter. If your filter is clogged then your restricting the air flow back to furnace creating ice up. Supply and return on demand. Don't have one then you won't get the other

Well if it's 78 then it's at least attempting to cool. Go to the front of the air handler an pull the black rubber insulation back on the bigger copper line. When the AC is in cool this line should be cold. Fairly cold if your cooling correctly. Also, if u have a stand that your unit is sitting on with an open bottom, then pull the filter out and get a flashlight and look into the bottom. If your coils look like snow white ice. Then your unit is icing up and u aren't getting the proper return. Check these two things and let us kno what u see.

Does the AC fans and compressor motors work? Is there power to the AC ?

Thermostat may be faulty