Notification mistake

I think this is my fault, I threw a switch thinking it would be interesting and now it’s bothering me and I want to turn it off. If I do copy and paste from one app to another or from an app to a search engine or from anything to anything --after I copy and paste it, a drop-down notification tells me what I just did. Well, I know I did it I don’t need the app to tell me. The drop-down Notification is actually making it difficult for me to do other things because it’s blocking the screen so I sit and wait till it goes away. How do I turn it off?