My apple watch band is not clicking into it’s place

I bought the apple watch a week, and after two days a take off the band to clean. then the band didn’t click again.

I am really wondering where is the problem from the band or the watch.

I wish that a can solve it by my self

BTW just one doesn’t click, and when I exchanged the places of the bands it worked normal. but l didn’t feel comfortable this way.