For Sim Rate, the default is, you press “R”, then either CTRL + or CTRL - to increase or decrease the sim rate. That is, the CTRL key, followed by + or - keys. You repeat that again, to increase or decrease…
R then CTRL + or CTRL - . As mentioned, there is no visual que on screen when you increase or decrease the sim rate. I just look at the current time on the Garmin to figure out when I’m back to 1x speed.