I know it can be frustrating!
don't have this machine but as others have said it is most likely something simple
We have all had these problems!
My suggestion take everything off the machine and start over.
Instruction book in hand, put in a new needle, new thread, rethread the bobbin(making sure the thread is running in the right direction).
then adjust the tension to what the manufacturer suggests
if you still have problems set the tension almost as high as it will go and test.
is it better or worse? or the same
now set it as low as you can and retest
if there is still not a difference
maybe it is the machine and not user error