Hmmmm.....
I'm really sorry to have to tell you this, but you've made a big NO NO adding 2 SDs to a 10 gallon tank. Some SDs get up to 8" long and 6" tall in an aquarium!!
My only advice to you would be to buy a 55 gallon.....or take them back to where you bought them ASAP!
Sorry, but it's the cold hard truth
Silver Dollars prefer subdued lighting and that is probably why they are in the dark corner. That and they just may be adjusting to not being a big school. Correct me if I'm wrong but you probably bought them at a LFS that had a ton of them in the tank, right?
They will need some time to adjust. What I normally would suggest is that you go and buy 1-2 more, but in a 10 gallon tank I couldn't live with myself if I gave you that advice
They are a schooling fish and by all means they need a few of their own kind around them to feel comfortable. Even with 4, like myself, they still get very nervous.
Until you decide what you are going to do........try feeding them peas if you have any around (shelled peas) or do you have any shrimp pellets or algae wafer?? They will eat those too. You could try some lettuce or cucumbers also.
I hope I didn't overstep, I just think they would be happier if you took them back and exchanged them for some other smaller fish.
They really do need a LOT more space then a 10 gallon