Take a bit of cotton (sewing thread) and go through the loop. Pull both ends together, now you have the loop from your sweater held in the thread loop you've just made. Put both ends of the thread through the eye of a needle. Now you have on one side of the needle's eye two thread ends, on the other side a thread loop, which holds the loop from your sweater. Plunge needle into the centre of the pull and pull right the way through to the inside. The pull will be on the inside of the garment and will not be seen. Just full the fabric a bit in all directions and it will have disappeared totally. (Tricks my mother told me.)
Just full the fabric a bit in all directions and it will have disappeared totally. Put it on a lamp-shade too see the to see sewing threads in details. Take something enough thin to enter behind sewing threads and spread where it is too tight and it will be ok. I already have had 3/4 cm threads out on many spots (some where even broken but it was 2 fold) and managed to fix them all this way.