We can express tension as thread tension. From the tension setting, the upper and lower thread are moved to the fabric with equal tension and form stitches. This is an important issue because it is one of the most important factors affecting the quality of the product.
Here you have some warnings before you set up your machines. Firstly, make sure that you have opened your machine correctly. Make sure that your yarn is of good quality, your machine parts are undamaged, you thread the yarn towards the machine and that you have correctly and carefully positioned the yarn. Before you start your sewing projects, you should use sewing on an unnecessary part with fabric and thread. Double your fabric.
One of the problems is that the upper thread, which is very tense, is pulled up from the lower thread lock points. This means that the bottom thread is visible on the fabric side. The upper yarn is entirely on the surface of the fabric. Loosen the upper thread tension setting and try again. If the blood pressure dial has numbers, the tension will decrease as the number decreases.
In another case, the loose upper yarn is pulled under the fabric by the lower yarn, which is more strained. So the upper thread appears under the fabric. Increase the upper thread tension a little and try again. If there are numbers on the blood pressure dial, the tension will increase as the number grows
Ideally, you should try playing with small tiny tension adjustments up to the reach of the stairs. If any of the problems you see above on your sewing are present and the solutions I suggest are not working, remove the thread and re-install it properly. If you skip a single yarn guide, the problem may occur.