Glad to "hear" that you're trying Gimp again! I was having trouble too. Try clicking twice on the tool that you want to use (paint brush, paint bucket, etc), that worked for me. I'm definitely not skilled in using Gimp. Everything I wanted to make work I had to click on it twice.

I'm pretty sure you've seen BayouBlonde's Gimp Tutorial. Have you seen Krystal's Gimp Tutorial Video? One on changing colors can be found here. Good luck Seashall.