Why does thread gather in bobbin area and jam machine

Sounds like birds nest or thread nests. HINT: When threading the top thread, ALWAYS have the presser foot in the RAISED position.

Birds nest under the fabric big loops of thread top side looks good...

What causes Bird Nests Superior Threads

Sewing Machine Thread Bunching Up Here Why

That is what is referred to as bird nesting or thread nesting. It usually results from mis-threading, the thread not being fully seated in the tension disk, or the tension set too loose. (I have a machine that does this frequently because the thread "jumps" out of the take up lever when sewing fast--instant thread mess.)

Remove the thread from the machine. ALWAYS RAISE the presser foot and rethread from the beginning. Make sure the thread path is correct. Set the upper tension to the midway point between high & low number. (You will probably need to tweak the upper tension because every machine differs over time, but the midway point is the factory standard setting.)

While you are at it, check to make sure the bobbin is loaded and threaded correctly in the bobbin case.

If you continue to have issues, you may need to take it for service.

Sewing Machine Thread Bunching Up Here Why

What causes Bird Nests Superior Threads

Birds nest under the fabric big loops of thread top side looks good...

adjust the tension to a appropriate setting,
See the video here.
Sewing Help Sewing Machine Problem Thread Bunching Under Fabric
The knob and its location can differ based on the model of your sewing machine.

Usually this is a tension problem. On mechanical machines, you'd adjust the dial, or possibly even the bobbin tension. But on a computer machine, I don't know how you set the upper tension, sorry to say.

Sometimes it can help to unthread and rethread a machine, and I don't know why it sometimes works, but it's a simple thing to try.

But if the upper tension isn't set correctly for the work being done or if the tension mechanism, however that's handled on a computer machine, isn't working correctly, this is what happens. Bird's nest is a good way to describe it.

Sometimes lint built up in the bobbin case can cause this symptom too, but I'd assume you keep this area clean. One reason I haven't yet invested in a computer machine is because problems like this often don't have such simple solutions as on the mechanical machines.

After you put the bobbin case in, release it, and then pull on it to make sure it is in correctly.
The gathering is called a "bird's nest", and is caused by the machine not being threaded correctly.
Rethread the machine top and bobbin.
Then, sew a test stitch on a scrap of like material.

There are a few problems this could be. Your top thread could be broken or about to break; your bobbin thread could be broken, about to break or empty/about to become empty and is loose around the bobbin; you could have a birds' nest (a mass of thread just under the fabric/presser foot and/or within the feed dog and bobbin) forming and causing a jam; or it could be your Futura having a little bit of a hissy fit. Obviously, if you've checked for broken thread you need to move on. Check for a birds' nest by removing the fabric and clip your threads. If you find one, clear it, rethread your bobbin and begin sewing again. If there's no birds' nest, then place the fabric back in and try sewing/embroidering again. If the machine acts up again, I recommend removing the fabric/hoop, rethreading your top and bobbin threads, replacing fabric/hoop and resuming where you left off. If the machine still gives you trouble, try hitting the start button for a couple of times and seeing if the problem doesn't simply resolve itself. When you're embroidering areas that have a few small, short stitches only, the machine seems to act up a little and then behaves fine once you bypass the area. Be sure to take all of the other steps first, though, because a birds' nest will RUIN a beautiful seam or embroidery.

This annoys the heck out of me, cause it happens a lot more than it should. There can be some valid reasons as to why it happens, though.

Your top thread could be broken or about to break; your bobbin thread could be broken, about to break or empty/about to become empty and is loose around the bobbin; you could have a birds' nest (a mass of thread just under the fabric/presser foot and/or within the feed dog and bobbin) forming and causing a jam; or it could be your Futura having a little bit of a hissy fit. Obviously, if you've checked for broken thread you need to move on. Check for a birds' nest by removing the fabric and clip your threads. If you find one, clear it, rethread your bobbin and begin sewing again. If there's no birds' nest, then place the fabric back in and try sewing/embroidering again. If the machine acts up again, I recommend removing the fabric/hoop, rethreading your top and bobbin threads, replacing fabric/hoop and resuming where you left off. If the machine still gives you trouble, try hitting the start button for a couple of times and seeing if the problem doesn't simply resolve itself. When you're embroidering areas that have a few small, short stitches only, the machine seems to act up a little and then behaves fine once you bypass the area. Be sure to take all of the other steps first, though, because a birds' nest will RUIN a beautiful seam or embroidery.

Perhaps the needle thread tension is too loose for the material your sewing. It could be that your thread dog is clogged with thread (this has happened to me) Check your bobbin, perhaps its just wound poorly.
OR the needle you are using is too fine/heavy for the thread.

It could be that your thread dog is clogged with thread (this has happened to me) Check your bobbin, perhaps its just wound poorly.
Perhaps the needle thread tension is too loose for the material your sewing. OR the needle you are using is too fine/heavy for the thread.