Ok. So after almost a year of having problems with my podcast's artwork and SC being unable to help, I finally figured it out by myself (thanks for nothing SC).
1) Try this first (DIDN'T WORK FOR ME)but you might want to: https://soundcloudcommunity.com/podcasting-230062/i-cannot-get-my-podcast-artworkimage-to-change-on-the-itunes-search-page-6653478
2) Then you might try doing what Soundcloud suggested this via their "support" email but i had already done all of that and it DIDN'T WORK FOR ME:
a. Check and enable an episode for podcasting: head to the track's edit page (pencil icon under the waveform) and select the permissions tab. Click on the option that says 'Include in RSS feed'
b. Check to see you've set the category for your podcast on your Content settings page here
c. Make sure your profile image is 1400x1400 pixels. This is the default size for images on iTunes. ====>>>> THIS IS WTONG BTW (it can do up to 3000 pixels)
NOW, for the real solution:
1) Go to Settings => Content and copy the RSS feed.
2) Go to https://podcastsconnect.apple.com and sign-in
3) Click on your podcast and you'll see "URL". This "sort of" contains your RSS but in a weird, abbreviated way. FIX THAT by pasting the real RSS you just copied from soundcloud. Then, you can either click enter or "Refresh feed"
4) Apple will mark your podcast as "scheduled for updating/refreshing" (or sth else but I can exactly remember, sorry :$) You podcast will have a yellow dot right next to it. That means it's retrieving the info. Wait 12 to 24 hours.
I don't know if it works for RSS feeds that aren't podcasts this might you some ideas.