how do you copy and paste a cheat into the cheat bar instead of having to type it please?

You don't. (Edit: Okay, maybe @SimplyJen does have a way to suggest as below). But if you use NRaas Overwatch, you can add the console commands you like to it one time each and then run them from an Overwatch menu instead of typing them out using the cheats console. A common one, testingcheatsenabled true/false, is already accounted for.

This won't work for commands that have something like a sim's name at the end, but rather for ones that stand alone or always end in on/off or true/false.