@ Annatar11, thanks for the reply.
I'm using the keys on the top row. It appears what happened was I depressed and held the - key down and I received no message. The reason for this was that once you pass the lowest or highest speed setting you can keep clicking but no more messages appear. I'm not sure why no messages appeared initially appeared; perhaps I missed them, but I never got the confirmation clicks either.
A PC reboot and game reload and I now get the message and confirmation click for each speed update at the top center of the screen.
If however you are pressing the + key and keep clicking after the "Game update rate changed to 8x" message, you will get the confirmation click but no further messages. Same thing if you click - after getting the 1x message.
I'm still unclear though exactly what it means: " Game update rate changed.." I understand your reference to replay (like a sports replay in slow motion) Perhaps that is what these Keys are for to change the Replay speed of a recorded game?
I thought, being an RTS game, perhaps gamespeed referred to an overall slowing down of the games so old geezers like myself don't have to click on things with the lightning speed of youth
You know like a way to compensate for arthritic fingers, addled minds, and such 