Tying Rambam Chulyot Tight

Using your videos off of Youtube and much trial and error, I was able to correctly tie the Tzitzit according the Rambam. However every time I tie them they stay tight for a few days, then begin to become loose again, with many of the chulyot bunching together. I have tried tying them tighter and still no luck. Do you have any advice?

Looking at the step by step description
(https://www.tekhelet.com/diagrams/RambamDetailInstructionLORES.pdf), when doing steps 32-36, you should try to wrap the blue quite snugly. Then after you pull the blue string through (step 39) you should make sure the string is pulled through (FIRMLY), don’t pull too hard or yank, because the string will snap, but you do need to pull firmly to make sure the hulya is now a strong knot.
– Mois Navon