standard clock troubles

I thought I had that problem some months ago.  I wanted to change the format and checked the button for the format I wanted, exited display settings and was surprised when I saw that the clock format had not changed.  Contrary to nearly every other use of a button on any device that use them you cannot use a stylus and simply touch the button to select.

You have to actually touch the item itself.  If you have for example the Normal setting and you want the Dual format you would tap with the body of the item descriptor.