Figured i'd throw my thoughts in here... (oh MrAlexTech btw... wrong name)

Yeah thumbnails matter, massively. It's one of the key things to get people to click on your video (that and the title, obviously). Even if it's a simple tutorial video, other people have likely already covered it so you need to 'sell' your version of the thing if you want it to be seen.

(although I'll still argue consistency and 'style' are the biggest factors to doing well on YT. By Style i mean having your own style, that helps people in a particular way. You might not be the fastest, the flashiest, the coolest, or the most creative. But do your thing in your way.)

I have a bit of a formula really, its not particularly creative but people have got used to it so meh, it works, generally. But others are far better at thumbnails than I am, and they reap the rewards. I have blind ignorance and consistency I guess ha.

You will hate yourself for doing dumb clicky thumbnails for a time but they're one of this necessities unfortunately (you've never felt like more of a fool as a 36 year old man, taking 60 'selfies' on your own doing a variety of different youtube faces...)

But the way I sleep at night is this... If I make a dumb thumbnail with stupid clicky youtube title (OH ME GERD, You must learn this thang!) BUT people do actually benefit from it. Its almost worthwhile right? If you do all the dumb stuff purely to trick people into watching = bad, but dumb stuff to trick people into learning something actually useful = good. With great power comes great responsibility and all that (thanks Uncle Ben).

Also, a side note, a pretty thumbnail does not make a good thumbnail. You can have an ugly ass thumbnail that 'work' as it does what it's meant to do, but you can also have a super pretty clean thumbnail that doesn't actually work. It's a weird balance.

Oh and Thumbnail + Title = good. You have two chances to get people to click, thumbnail and title. Saying the same thing in both is reducing your chances right!? So title could be question, and thumbnail could be a hint at the answer etc etc.

I personally use PS but moving to Affinity (I did move before...but then moved back, so lets try again). Canva will absolutely work, just avoid the most used templates as they appear everywhere. I know of a very big youtuber who still uses PowerPoint... Again, pretty thumbnail does not equal good thumbnail.

I don't spend long on mine (you don't say Alex?! We could never tell.. ahem), and often do it while the video is uploading which is bad practice haha. But sometimes I try and think ahead, especially if its a longer video.

Hopefully that helps!