The Omega One should float for at least a little while, my bettas don't give it a chance to sink, they snatch it as soon as it hits the water. If I hold the pellet in my fingers too long it sinks faster or if I drop it from too high up. I feed NLS, some of the pellets float longer than others but again my bettas typically get most of the pellets before they sink. I don't think your Bettas are confused they're just little piggies.
I can feed my bettas they're food then feed my snails algae wafers or veggies & the bettas will munch on them, that's just what they do. I've quit fighting it other than to not feed the snails more than 2-3 times a week. This, I believe, makes the snails do their clean up job.