STEP 1: First off, locate the levelling stud at the bottom of your Titus desk leg. Gently turn it anti-clockwise until it becomes detached.

STEP 2: Before proceeding, ensure your caster is in its locked position. Then, place it into the now unoccupied hole. A few gentle clockwise turns should securely fix it into position

STEP 3: Well done so far! Now, all that's left to do is replicate Steps 1 and 2 for the remaining three locking casters. Once you've completed this step, your task is complete.