does 2020 Prime have "Charge Current" 12amp OR 8amp setting?

Default is 12 amp. If your charging is taking longer than ~6 hrs, then as you said, you might have changed the charge current to 8 Amp. The charge current is still changeable thru the "Vehicle Settings" in the MID. The menu listing may be slightly different from 2017 as shown in the video, but it is under the "Vehicle Settings" and then "Charge Settings". Here is the copy of the manual for a 2020 PP.

 

Yes. Actually, it switches between 8A and Max since if you have an L2 charger it'll go up to 16A.

No, but you can set it to 8A if you have other things on the circuit and the breaker trips.

It should be there. I'm not sure why the video has the guy going so many steps to the right to get to vehicle settings when two clicks to the left would have done the same. (It wraps.)

No, unless you consider the owner to be a fancy computer.



Note on the extension cord. The owners manual says to not use one, but most people seem to assume that was written by a lawyer. Still, you want to keep it has heavy and short as you can because it will heat up more than not having one. 12 ga. copper would be minimum (and probably as big as you will find, too). Make sure the plugs don't get too hot.

 

Jerry & Sal instructions to get to that menu is correct; but the options are kinda hidden. Once you get into that screen, there are no options (it's blank) - you need to toggle up or down to display options. I don't know if that's a software bug or they did it on purpose to make it a bit more difficult to access those (higher level) controls.
Someone at the dealership inputted the wrong date into my car - couldn't figure out why my scheduled charging was behaving badly. Once I figured this out; everything started working as expected.

 

Yes, the owner's manual is a way better friend than the dealership.