Hi Mike, Welcome back to A:M!
CTRL-C and CTRL-V do indeed copy and paste keyframes but there are options you need to be aware of to get the result you want.
Keyframing in A:M is very powerful so there is potentially lots to know but here are the basics.
(Note that at 1:48 I speak of individually selecting several bones. I am holding down the CTRL key while I do that)
PRJ shown in the video: ThomKneeBends002 in Action.prj
KeyFrameCopyPaste.mp4