I learned this from a 'seasoned' Frontosa breeder/keeper.
1. Problem might be you are feeding too much. So hold off on feeding for a day or two.
2. Feed frozen food such as Hikari Krill and/or mysis shrimp. I have stopped feeding pellets myself...too much waste and the greedy ones tend to get bloat. Nitrates are much more manageable too. Even the person I buy my WC Fronts recommend flakes and krills too. I also use Spirulina Flakes every other day.
3. Get around 3 cubes of the Hikari Krill cubes, place them in a coffee cup or a container that you will always use. Fish will associate that cup and container as 'feeding time. Thaw the frozen krill. You can also sprinkle garlic powder for taste enhancer, and oh garlic is also good for them.
4. Feed them.
5. As they learn this process, only feed them when they come out.
6. You might also consider getting rid of most of the caves....Frontosas really do not need them.
I did this with my colony of adult WC Kitumbas....wala by the 3rd day, they were eating Spirulina Flakes from my hand.