It seems that Yamaha has provided more than one style of adjuster; this is one of them.
Some are like the one shown in the Owner's Manual; some are different, like this one.

The bright vertical bars on each side near the top of the above photo are the fixed stops/setting indicators.
The stepped ramps above the squarish holes give the various settings. (the other ramp is on the back side)
The squarish holes are where you hook the spanner wrench (adjusting tool).
No numbers are visible on this adjuster, but the shortest step would be 1; the tallest, 9.
The shortest step gives the softest ride but is more likely to bottom out on bumps and dips.
The tallest step gives the hardest ride but is less likely to bottom out.
The factory setting was near the middle step, either 3 or 4.

Hook the spanner wrench (looks like a "J" shaped piece of flat metal) into a squarish hole, put the flattened tube over the handle end of the spanner wrench, put a longer bar or other tool into the flattened tube (for leverage) and turn the cylinder with the steps whichever direction it takes
to get to the setting you want.