I was installing sheetrock in my garage and had to disconnect the wires to my heater blower. It has a wall switch installed and I turned the switch off and did a voltage check. The black was plenty hot. Discovered that they installed the switch on the common or white wire. I changed it out and installed the switch in the black. So I checked the lighting switches and they are the same. I am thinking I should correct the light switches too. Am I overly concerned?

hello: currently I am adding a bathroom ceiling fan to a house with aluminiun wiring. The light for the bathroom is on the wall, I disconnected the wire from the light to the switch, pulled the wire out up to the attic and cut it, now there is 14 guage wire from the switch to the attic. I put a junction box in the attic where the wire from light, wire from switch and wire from fan all join. I joined all three black together and all three white together, then I joined the three ground and a peice of copper wire together and ground the copper wire to the box. When switch is off light is on a little and the fan is going, when switch is on light is on but fan is off. Any help wounl be emensly appreciated thanks.