how do you keep the yarn ends from popping out after you weave them in and trim them ?
What kind of yarn are you using (is it slippery?)? How are you weaving the ends? How long is your weave? Certain yarns may necessitate the ends being stitched with a bit of thread. I don’t use slippery yarns but do use a lot of recycled yarns that have unplied threads. With that, or acrylics (when needed), I use a dab of FrayCheck.
ETA: neglected to mention I always use some form of dupe st to weave. Nearly impossible for ends to find their way out with that method.
When I weave in the ends I used to go in and out of the purl bumps in ONE row, but they can flip right out so I just put the yarn on the yarn needle and weave it straight down the piece . It won’t move. It would take a lot of force to get them out.