No conversion, it would need to be replaced with a single handle faucet.
Moen part #1920 and a brand new Moen single handle faucet
Change the faucet, either one will mount on the sink.
Turn the water off to the faucet. Remove the handle. The top of the faucet should unscrew to get to the ball valve. Replace the valve and gaskets then reassemble the faucet.
Look under the handle for a small ALLEN SCREW (hex head). Loosen it and slide the handle off.
A single handle uses the same 3 holes as the double handle
You have a cross connection on a faucet somewhere in the house. That means the hot is overriding the cold because of a malfunctioning faucet. Usually happens at the tub/shower diverter if it is a single handle.
First make sure that the hot and cold supply lines (the plumbing) aren't backwards (hot should be on the left as you are facing the faucet) or that someone accidentally ran two hot lines. For the problem to be in the faucet itself you would have to have a single handle faucet. If this is the case the control valve is broken and should be replaced. Three handle Left= Hot Water Flow. Right= Cold Water Flow Center= Controls whether the water comes out the shower head or tub faucet. Two handle Left= Hot Water Flow Right= Cold Water Flow (Diverter Valve is elsewhere if it's a tub/shower) Single handle One handle controls both water pressure and temperature
On the single lever handle just unscrew it.
If this faucet was recently purchased, return it to the store because you do not have the proper parts. If the screw will not go in, the threading is wrong, or the threading is stripped, or there's still something in the hole preventing it. You won't be able to attach it securely any other way.
Have you got two single faucets or a single lever faucet? It could be a pressure imbalance or it could just need maintenance
The handle must be removed to allow access to the retainer clip, then the cartridge pulls out. You may need a cartridge puller if the faucet is old.
You need to buy the extractor tool from Home Depot.