Your lid or cap is not sealing properly, and coffee is leaking from the rim? Then please check the following points first:

Is there a sealing ring in the lid? If not, we’re happy to send you one (email to service(at)kaffeeform.com). Is the sealing ring positioned correctly? Ensure it’s not twisted.

Initially, it may take a few attempts to get the lid properly closed. Try it over the sink first. Place the lid straight, i.e., horizontally, on the cup. Turn it to the left counterclockwise until it clicks. Only then screw the lid tightly to the right clockwise.
Please find a video instruction below:

If it’s still leaking, feel free to contact service(at)kaffeeform.com, and we’ll replace your lid. You have a double-walled cup, and it’s leaking or falling apart at the seam? Please also contact service(at)kaffeeform.com, and we’ll replace your cup.