SAN FRANCISCO (AP) -- Microsoft is retooling the latest version of its Windows operating system to address complaints and confusion that have been blamed for deepening a slump in personal computer sales.

The tuneup announced Tuesday won't be released to consumers and businesses until later this year. The changes, part of a software package given the codename "Blue," are a tacit acknowledgment of the shortcomings in Windows 8, a radical overhaul of Microsoft Corp.'s ubiquitous operating system.

With the makeover it released last October, Microsoft hoped to play a more prominent role in the growing mobile device market while still maintaining its dominance in PCs. But Windows 8's design, which emphasizes interactive tiles and touch controls, seems to have befuddled as many people as it has impressed. One leading research firm, International Data Corp., says Windows 8 contributed to a 14 percent decline in worldwide PC sales during the first three months of the year -- the biggest year-over-year drop ever.

Meanwhile, sales of smartphones and tablet computers are booming. The biggest beneficiaries have been Apple Inc., the maker of the iPhone and iPad, and Samsung Electronics Co., which sells the most devices running on Google Inc.'s Android software.

By contrast, leading PC makers such as Hewlett-Packard Co. and Dell Inc., which primarily sell Windows-powered machines, have been mired in a financial funk that has battered their stocks and raised questions about their futures.

Despite the troubling signs, Microsoft insists it's pleased with Windows 8's performance.

Reller said Microsoft still realized changes need to be made to make Windows 8 easier to navigate and capable of taking full advantage of technology improvements that have come out since October.

"Are there things that we can do to improve the experience? Absolutely," he said "There is a learning curve (to Windows 8) and we can work to address that."