Honestly, I want you do enjoy coming here and I want you to feel free to ask for advice. It's up to you to take it or leave it, of course. So let's not get off on the wrong foot. I apologise if my message seemed rude to you. That wasn't my intention. All I meant was that if you don't do anything, the fish will likely die, no matter how carefully you watch it.
Unfortunately it is all too common for people to end up with essentially incompatible fish. Rainbow sharks and mollies shouldn't be kept in the same aquarium. They have different requirements. Over the long term, you need to choose which you prefer, and buy fishes suited to that fish. If you like the mollies, then get hard water/brackish water species, like guppies, rainbowfish, halfbeaks, glassfish, or gobies. If you like the rainbow sharks better, then rasboras, gouramis, Corydoras, and angelfish would all be suitable.
Cheers,
Neale