Why are both wires white and black hot at the outlet, light switch and even at light in the ceiling. I replaced the outlets and switches and lights
In the case of a light switch, it is normal if the switch is setup as follows:

[elec ]B=========#==============+
[panel]W--------+ +X---------X+ |        
                | |           | |   
                (~)           [-]
               light         switch


The white wire is carrying power back to the light, and convention dictates there should be a piece of black tape (X) around the white wire to indicate it is a live return.

It's important that the switch must go against the live lead not the neutral.

-- Minor edit to diagram.  The wire from the panel usually ends in the ceiling.  A new wire runs to the switch, black to black with a nut, and white (switched hot) back to the fixture. # indicates this nut.