Notification delete?

Good afternoon, for a few days I have a small failure in the clock and when a notification arrives, it jumps and clears itself. Is there an option that has been activated that causes the notifications to be deleted? What can I do to keep the notifications until I dismiss them? Thank you

We can’t read your mind. I believe to assist you will require more information about your issue. For example which notifications are you referring to, the ones from the watch or the ones from your connected phone? Is the screen turning off (going black) or staying on (what is the sleep setting for your display)? Have you made adjustments to how your watch responds to notifications etc.?

They are in all the notifications of both the clock and the mobile phone, when a notification arrives the clock vibrates and when I turn on the screen to see the message appears and in less than a second the notification disappears without touching anything

Again without more information its hard to help. Which connecting app are you using? WiiWatch, Watch Droid or other? I exclusively use Watch Droid, version 9.0. with my watches running Android 7.1. When notifications appear on my watches they are open on the screen and I have whatever the sleep time, usually set to 30 seconds to respond. I do not have to turn on the screen, to read the notifications.
As I read your initial post it did not always work this way but just started.
Without knowing what you have done with the watch ie. updated the firmware, which apps you have installed, settings you’ve adjusted, A Factory Reset is where I would start. Because, to me, this is not a normal response to the notification process and would put your watch back in its original condition before the issue started.