Prior to Cubase, I lived for many years in the Cakewalk / Sonar world. In that environment, you could simply double click on a marker to edit the name, a trick that doesn’t seem to work in Cubase.
Currently, to rename a marker, this is the process I take:
Select the locate / markers track.
In the markers pane at far left, go down to the bottom, select the horizontal scroll bar, and drag it to the right so that I can see the marker names (my resolution is 1920x1080 but there doesn’t seem to be a way to widen this pane to show more than the id and position, so I have to scroll the pane).
Double click in the Description field for the appropriate marker and edit.
As you can imagine, this is exceedingly tedious to do on a regular basis. It wouldn’t surprise me to learn that I’ve overlooked a simpler way to accomplish this, so I’m hoping someone can point me in that direction.