It has been awhile since I tinkered with a Mohave. However, I am guessing that the ABC settings are your string posts. Almost all of these style cams come with the string attached to the middle post...in this case a "B" setting. Moving the string position on both sides of the cam to either the A or C setting should move draw length approximately one half of one inch. Moving the string the post closer to the center of the cam shortens draw length while moving it to the outer post lengthens it.

Hope this helps.