I am personally using photoshop and had my license for 4-5 old photoshop which I got from my previous job.
But looking at your thumbnails I'd say one thing to keep in mind is to set font size to be slightly larger than you have them right now.
I've noticed in last couple of videos you've published that you have more views on videos that have text in thumbnail(that doesn't mean you get better watch time).
A bonus tip - I'd say for your live streams, it might not be a bad idea to not publish them all as videos as it will lower your view time overall since videos are 1-2hrs long.
Unless you have people actually staying on for such long periods which is amazing
Your best performing thumbnails overall are with closeups of people faces so I'd say keep that in mind as well
