Walmart Inc.’s new U.S. chief wasted no time putting his stamp on the unit, appointing his former top lieutenant as second in command and parting ways with the retailer’s head of merchandising.

In India, an unfavorable e-commerce ruling is likely to crimp the growth for Walmart Inc. In China, the retailer says an economic slowdown has shoppers tightening their purse strings. And now in the U.K., a deal to reduce Walmart’s exposure to the slowing market there is on life support.