For this type of pool coping you are looking at both the cracks and the track itself fatiguing and expanding, allowing the liner to fall out in some places. The permanent remedy is to remove the coping stones above the entire coping track, and if you go with the same (looks like it is Cinderella CP2 Bullnose Coping), it would need to be replaced and concrete repoured over it to hold it in place, and then put pavers back on top. This can only be done at the same time as a liner replacement. Alternatively, if this coping is removed, a surface mount coping could be put back to replace it, and then you can repour a track for the coping to sit on. Either way, it’s a major renovation. In the meantime, if you fill the cracks with caulk and touch up with a white paint, and use pennies to hold the liner up in the track in the places it has fallen out, that is a work around cosmetic fix, and much more inexpensive. It just depends on how much you want to spend.