Clipboard - how can I use as I want to?

English Applications
1

I want to only put things in clipboard when I want to, not every time I accidentally or otherwise swipe across some text or whatever with my mouse.
Cut and copy I can understand, and use it for that often. But digging through dross to find what I purposely put there is a bother.

I have looked for settings but not finding any that control when and how it is used.

2

***Never mind! Head is finally out of dark place where this is concerned!
How do I delete a post after it is already up? And is there a strike-through option?

3

You can’t…best just to post that it is resolved, and preferably with some details to assist the next person who may come searching.