Thanks for all your comments. I removed the crummy stitches and rethreaded with green by pulling the thread thru. I didn't change the tension, but made sure that the thread was correctly seated in the tension disks. Stitched a sample and it was just fine, so it was operator error. I haven't done many quilts with multiple color threads, but I must have just been lucky in the past. From your comments and my bad experience, I can see that I need to check my tension with each color change in the future.
Thanks!!!!!

I cut the thread and tie new thread on but I do not pull it thru the tension disk I had troubles when I pulled it thru the tension disk so I cut the tie threads off and then I put it thru the tension disk it has worked so far for me doing it this way.

Yep... Been there and done it. Learned a valuable lesson. When I change colors of threads or different kinds, I have to practice on a scrap first. Even if you just run a few lines on the side or top of the quilt to make sure everything is working right. Sorry, you had this problem too.

I used to have tension issues even from bobbin to bobbin with the same spool of thread until I switched to Glide (www.BobbinCentral.com) and haven't had a single issue since switching to Glide. Love that stuff... I still check after I put in a new bobbin but haven't had to adjust the tension ever. Love Glide.