Ok just added option to disable Instagram and Twitter from ▼ menu on the right of the search input. Let me know if that works good for you! Stackoverflow is there right now. Not sure how best to trigger HN, let me know if you have any suggestions on that. Probably not good to show it all the time.
I did test the Google column wider for a couple of weeks, but ended up changing it the same as the other columns. Design wise it came out that consistency was a lot more valuable for UX. Let me know after you use it for a while and get use to things, I will reconsider adding this if it still would help you!
On ordering, you mean manually? Right now I am trying to do that all automatically without thinking or manual settings, and trying to optimize for relevancy. Let me know more about your problems or ideas here.
For changes, right now based on all the feedback, seems like I should consider more sources, sort options, and dark mode?