How do I manage storage on my Apple Watch?

Every day for a week now I’ve had to repair and unpair and repair my watch to my phone. The storage keeps getting full. The message app keeps filling up my storage on the watch. My phone storage for the message app is only 5 GB. But for some reason, the watch storage says the message app is 18 GB. I don’t understand why they’re not the same. I don’t understand why it keeps filling up my storage on the watch. Please help to remedy this problem. I did not have this problem until an update occurred.

[Re-Titled by Moderator]