I had a clock that I could change time with, but it didn't work if I showed it to people.
In dreams, clocks often symbolize our perception of time and how we handle it in our waking lives. The fact that you had a clock that you could change time with suggests a desire for control or influence over the passing of time or the events in your life. This dream may indicate a longing to be able to manipulate time or change circumstances to better suit your own desires.
The fact that the clock didn't work if you showed it to people represents the idea that this desire for control and influence may be something you prefer to keep private or hidden from others. It could suggest that you feel that others may not understand or approve of your desire for control, causing it to lose its power or effectiveness.
Overall, this dream suggests a desire for control and influence over your own life, but also highlights a fear or hesitation of expressing this desire openly to others. It may be worth reflecting on why you feel the need for such control and whether there are healthier ways to address these underlying needs and desires.