You may want to create tests that are built from “random blocks” from pools. This means that you have a pool with 80 questions, say, and an exam that randomly pulls 20 of those per student. Each student gets a unique (or as close to unique as statistically possible) test.
These pools often come from publisher test banks, but you may not want to use all of the questions, or you may want to emphasize having that random pull factor, giving different questions to different students. Either way, here’s a video guide to setting this up in your course.
How to Create Exams from Question Pools