After three years of steady declines, fall enrollment at Compton Community College has reached 3,588 students--up 10.5% over last year, officials said Wednesday. Final figures won’t be known until next week, when the school finishes signing up students interested in a special series of short-term courses, spokesman Charles Cropsey said. Classes began Sept. 4. Officials already view the enrollment boost as a further sign that the school--under the leadership of new President Edison O. Jackson--is shedding its image as a beleaguered institution. As of last year, the number of students had dropped 46% from 1981’s enrollment of 6,500.