Hi welcome to the board. In one way, it's nice that you are using different colors of thread for the top and bobbin. It makes it easier to diagnose the problem. Rule of thumb is if the problem is on the top (bobbin thread on top) your issue is with the bobbin. If the mess is on the bottom (top thread nests on bottom), your upper tension is off.
Having said that it is extremely difficult to balance top and bottom thread, so most people use the same color in both.
Now to your problem. Excess bobbin thread is showing on the top, correct? The first thing to try is clean your bobbin area thoroughly. Take off the foot plate. Get your manual out if you don't know how. Wind a fresh bobbin and make sure you are inserting it correctly.
Are the top and bobbin thread the same weight? if not, this can throw things off.
Unless you are trying a fancy stitch, your stitch width should be set for a straight stitch, probably 0. You do want to up your stitch length to at least 3 or 3.5.
Insert a new needle, top stitch or jeans is a good one to try.
Rethread.
Now practice on a scrap sandwich.
If this doesn't fix the problem, you may need to adjust your bobbin tension.
First examine your bobbin case. Make sure you don't have any lint in the tension spring area, and try to sew a sample again.
The last thing you can try is adjusting the bobbin tension. This can be a bit nerve wracking. TEENY TINY turns of the screw can make a huge difference. Use an extra fine tip sharpie and mark the original position of the screw. Sounds like you need to try tightening the tension a bit.
One final comment is to make sure that your quilt is well supported and it's not dragging anywhere.