You can use different Watch Faces on your Apple Watch and thus change the design according to mood or time.
You'll need to add a new Watch Face first. Here is a summary of how you can add a new Watch Face to your Apple Watch:
Adding a new Watch Face
1. Display the Watch Face (press the Digital Crown once)
2. Now press the display firmly with your finger and scroll to the right until you see a plus symbol.
3. Select the plus symbol
4. Now turn the digital crown until you find the Watch Face you want to use on your Smartwatch.
5. Touch the Watch Face to set it as your default Watch Face
6. Press and hold the newly added Watch Face again - select "Customize".
You can now make further changes to the Watch Face. Now you know how to add a Watch Face to the Apple Watch.
Deleting the Watch Face on the Apple Watch
1. Display your current Watch Face and then press the Apple Watch display firmly.
2. Scroll right or left to find the Watch Face you want to remove from your Apple Watch.
3. Swipe your finger up on the display, and then tap the Remove button.
You know how to add a new face to your Apple Watch or remove an existing face.