what has been the behavior over time of this machine? Is this a new problem, a problem that perhaps had never been observed in the past, or one that occured after some form of mechanical maintenance?
On scaling, these are just guidelines. What you look at should be based on the type of machine.
In general for a gearbox look out to about 2X+ of mesh. Some people recommend 3X+ of mesh. That would mean for this instance look out to about 600 Hz (36000 cpm) or 850 Hz to about 900 Hz. This would be your already provided plots out to 60000 cpm. I do see in one of the plots, something of low magnitude at around 16000 cpm, which might be the bevel mesh frequency.
Once you've looked out far enough to see mesh, 2X mesh, and perhaps 3X mesh, then pull in your sample frequency to look at the rotational components and some harmonics, perhaps out to about 5X. Your highest rotational is the bevel pinion at 990 cpm, so a plot out to about 5000 cpm would be desirable.
But your have to keep in mind the machine design. The sun pinion rotational is at 4.26 Hz or about 256 cpm, so it might be desirable to have a plot out to about 1000 cpm, roughly 4X of the sun pinion.
On scaling amplitute, I also suggest you scale everything the same. Currently your plots have amplitude scale ranging from 1.2 to 3.5 mm/sec. If everything was scaled to 3.5 mm/sec, it would be readily apparent which physical position had the highest level of concern.
Hopefully you can see that although one plot scale may get you the overall picture, you may have to zoom in on certain areas for diagnostic purposes.