Click a checkmark on the "REQUIRE IMMEDIATE PAYMENT" inside your ad, it's close to where you put your paypal address when you revise your ad.
Settings to you account email sender edit account
When you list your item for auction, do not include the buy it now option. Leave it blank, this is the same as commit to buy.
So you item will only sell to the highest bidder.
If you are selling at a fixed price. Then commit to buy / or buy it now is default. You can not remove this.
The issue is not your listing, its the buyers who do not complete their transactions and don't pay. They are a complete waste of time.
Commit to Buy is part of the Ebay payment system. You have no authority to change how they designed it. You dont have to sell on Ebay.