7-Eleven may have pioneered the convenience store concept in the U.S., but its lackluster reputation in the country is forcing a major transformation across its more than 12,000 stores there.  Nearly 70% of 7-Eleven parent company Seven & i's total revenue comes from North America, and the U.S. makes up the majority of that. Even so, sluggish performance has made the Japan-based company rethink its stores in the U.S."The U.S. side remains a huge question mark," said Lorraine Tan, director of equity research ...