Since you are having nitrates at that number your tank cycled or mostly so BUT what I think your ammonia problem is stemming from is the fact you've been grossly overfeeding. AND which tank is having the ammonia? You need to start posting the tank stats like...
10g
Ammonia
Nitrite
Nitrate
Ph
20g
Ammonia
Nitrite
Nitrate
Ph
Also post Goldfish or Community behind the 10g or 20g. It's hard to understand what tank is doing what otherwise. So for example if the tank having the ammonia problem happens to be the GF tank well GF produce ammonia, a lot of it, into the water. Add that to repeat overfeeding and that could be the problem. Are you following here? So get all the stats posted for each tank and then be very specific about which tank is having ammonia or other problems. This all needs to be separated out before going any further or offering any advice IMO.