If you're struggling with issues on your Mac (especially if the problems seem widespread), an easy thing to try is reinstalling the operating system. I know, I know, that sounds terrifying and risky, but I promise it's not. That said, I would definitely recommend creating a backup of your machine before you take this step, but that's always true. Heck, I recommend you make a backup of your machine before you do anything in life, from drinking coffee to walking your dog. It'll help you not end up making this face when your Mac crashes:
Yes, that's a stock photo of a cute baby. I needed an image for this article, and I was getting tired of pictures of computers, okay?
Anyway, to do this, start by shutting your Mac down completely. Then press the power button, and right after you do, hold down the Command key and the R key on your keyboard together. Keep holding them down until you see the Apple logo. After that, you should be taken to the macOS Recovery screen, where you can click on "Reinstall macOS" as Apple describes here.
Note, though, if you've got one of the fancy new M1 Macs, the process is a little different. For those, Apple says you need to do this:
Turn on your Mac and continue to press and hold the power button until you see the startup options window, which includes a gear icon labeled Options. Select Options, then click Continue.
But either way, following these steps can often resolve small persnickety problems and bigger ones, too. My most recent success was that reinstalling macOS fixed an email searching issue! Ah, temperamental computers. You gotta love 'em.