OAK BROOK, Ill. -- McDonald's Corp. is testing modifications to its popular $1 double cheeseburger, and higher prices for the sandwich, as it prepares to change its Dollar Menu by next year.

In an interview, Don Thompson, president of McDonald's U.S. business, said the company has tested ways to make the burger less expensive to make. Some restaurants are selling it with one slice of cheese instead of two, and billing it as a "double hamburger with cheese." Others are offering a double hamburger without cheese. Some are selling...