I remember watching your 3 attempts at bicep curls. The 3rd attempt in your previous post was the best although I'd say it was only 85% correct.
When you do bicep curls, slow down the pace. Keep your elbows pointing down so you focus the contraction purely on the bicep. Also too don't use momentum to try and pull the weight upwards, just pull it up from rest.
If I recall correctly you were still slightly shifting your elbows around when you were pulling it up, and sorta using an 'umpf' to get the weight going. Try going a bit lighter.