I want to report that at the section of grid there is not the option to change the beat marker
Can you take a screenshot to show what you mean?
What what traktor version are you running?
the first is TP4 & Second TP3
Yeah, it's now under grid.
It's separated because if you have a track with fluctuating BPM you can end up with 30+ grid marker and that would clutter the cue point UI.
Here is a video from NI about how to set grid marker:
I also made one, showcasing a track with fluctuating bpm where you can see a ton of grid markers in a track:
