I'm trying to grow lychees from seed but they keep molding over. Any ideas?

The fruit must be fresh as the seed is only viable for a couple days. If you are trying to grow seed from grocery store Lychee, the seed may no longer be viable. Lychee fruit are picked and cold stored for shipment so may be 2 or 3 weeks old before they get to the grocery.

The lychees I buy are red and fresh-looking. They are attached to their branches and aren't brown.

I know they are viable because some have germinated. So why then are they getting fungus?

Gerdener, I went the amateur route and just Googled your question and got a couple of answers which can be a start:

"Fungus is a sign that your soil is too wet. Soil that is overly wet can cause the. While it's important that your seed starting mix does not dry out and damage the young roots of your seedlings, it's equally important that it's not soggy. Check the mix in the containers daily to determine watering needs."

How do you get rid of fungus on seedlings? Another answer off Google
"To make this simply mix 1 teaspoon of 3% peroxide to 1 cup of water and use this to bottom water the seedlings with. I've found this is a great mold preventative in our seed starting. If you already have a mold problem or root rot then you can increase the peroxide to 1 tablespoon per 1 cup of water for treatment"

Spray the seeds with a biofungicide and then, after you plant, spray the soil surface. Biofungicides work because they contain living fungus but, the fungus are good fungus and stronger than the bad so attack and kill the bad fungus.

One of my family members recommended neem oil to me. I'll try it out since I already have some at home.

As to why I started this post in the first place, it's because the lychees are getting about as much water as the other plants and they have drainage holes, but the other plants don't seem to have fungus. Thank you for your advice, all of you.