Apple watch face keeps changing

Hi

You appear to be describing the result of accidental watch face interactions.

Under the current version of watchOS, swiping from edge to edge across the watch face switches between different watch faces that have been added to the collection on your Apple Watch.

If you tend to only use one watch face, then you may find it most convenient to remove any others from the collection on your Apple Watch, so that accidental swipes across the screen no longer select a different one.

Watch faces can be added back as and when desired, either directly on your Apple Watch or via the Watch app on your iPhone.

Follow the instructions here to select and manage your watch faces for your Apple Watch:

• Customize your watch face
• Change your watch face - Apple Support
• Faces and features