OP amp output not changing ( schematics )
The LM324 has an input common mode range of the negative rail up to two volts below the positive rail.

So with a five volt supply, you need to make sure your signals are in the 0-3 volt range for proper operation.

In no case should you apply a signal beyond the supply rails to the opamp's input, like 6.1 volts into a 5 volt-powered opamp.