I'm installing a GE wall oven. I have red, white, black and copper wires coming from the oven and the same coming from the wall. Do I connect each color wire to each other or do I connect the copper wires and white wires together?

If you only have a three wire feeder to the old unit, then the whites and bare can be connected. If at all possible, change the three wire cable to a 4 wire to match the oven.

Three wire feeder is still allowed for existing installations only, not allowed for new installations.