Changes in media sizes settings doesn't work

If you mean it doesn’t resize your old images, this is correct. There are plugins like Resize Thumbnails that can, but WP has never resized the old images.

Ah no I didn’t expect WordPress to resize the old photos. Good to know this plugin though, so thanks!

But I really mean that WordPress doesn’t resize my new uploaded images.. Hmmmm

The only time WP won’t resize your NEW images is if it can’t.

That is, if you set large to 400×500 and upload a 300×200 image, it won’t magically make a 400×500 sized image.

Also remember that your theme can override that.

The thing is that I don’t need those other sizes. So I want them to make like 0x0 or 1×1 pixels to prevent taking much space on my server.

But he doesn’t make the photos 1×1, although the media settings really says so. He’s not listening to the settings at all.. Hmmm..

Hah, okay, now THAT explains everything.

IIRC you have to set ALL the image sizes to 0x0 to make that work: https://www.wpbeginner.com/wp-tutorials/how-to-prevent-wordpress-from-generating-image-sizes/

Though frankly it’s a pretty rare case where anyone wants to.

Yes, it worked for most sites of my WordPress Multisite! Thanks so much for the help!

I’m still having problems with one Theme though. It makes like 7 different sizes for each photo. All media settings are on zero and I removed the functions. It’s weird. And when I remove an image, there’s still one size left (80×60).

Check the theme again, make sure it’s not calling it anymore, and check your plugins. One of them may be doing it.