Naughty Sewing Machine

Sometimes my machine seems to have a mind of it's own. One that has a completely different viewpoint to me. Spent this morning piecing some multi-colour fabric for a block in my sampler quilt, cleared everything away and had a break. Came back this afternoon wanting to piece two large White pieces for the backing of another quilt. Changed the bobbin and the top thread and sewed a test piece. Machine wasn't having any of it, tangles everywhere. Checked everything, found new bobbin and refilled, same result, changed top thread, same result, changed combination of threads, same result. By now starting to get annoyed. Put back bobbin and thread from this morning, green bobbin, dark cream top thread, and sewed perfectly. At this point I gave into the machine and now I have a seam on the white fabric sewn in green and green. At least it is only for the back of the quilt. Hopefully the sewing machine will let me make decisions about thread colour in future otherwise there could be some very unusual combinations happening