Wendy -

looks like you got a root rot - it is an infection, spreads fast, it is not because of the white mold on the surface - it can be bacterial or fungal. The only thing - white mold means that the soil is on a wet side - and it can make the plants more susceptible. Commercial AV soil is still too heavy - it would help if you add 30% of perlite to it.

Try again!

Correct ... try again ...

Baby violets don't need a lot of water. Just water them enough to keep the potting mix slightly damp, like a wrung-out rag.

Make sure that your potting mix has the requisite Pearlite mixed in (as Irina stated), and check to see if the AV potting mix you are using isn't ALREADY FERTILIZED. If your mix is ALREADY FERTILIZED, ... don't add any fertilizer for at least six months. If I use a pre-fertilized mix, as I do usually with no problems, I may wait until I get good growth and a first bloom before I start to add fertilizer.

Finally, check with your water provider to see if they use Chloramine in their water processing. If they do, then you will have to use another source for water (i.e. grocery Spring water, rain-water, etc.), because Chloramine will kill your African Violets.

I was never really able to successfully propagate new Violets, until I discovered that my water company used Chloramine, ... and then switched to using grocery Spring water to water my African Violets.