As of today, Apple has stopped signing iOS 9.3.2 and iOS 9.3.3 for compatible iPhone, iPad, and iPod touch models, meaning users can no longer upgrade or downgrade to those versions of iOS using iTunes. Apple is now only signing iOS 9.3.4.
iOS 9.3.2, initially released to the public on May 16, 2016, was an update that initially bricked some 9.7-inch iPad Pro devices until an updated version was released on June 2.
iOS 9.3.2 was followed by iOS 9.3.3, released on July 18, and iOS 9.3.4, released on August 4. iOS 9.3.2 and iOS 9.3.3 were both compatible with the recent Pangu iOS jailbreak software, which is disabled by iOS 9.3.4.
Now that Apple has stopped signing iOS 9.3.2 and iOS 9.3.3, it is no longer possible to downgrade to a version of iOS that supports the Pangu jailbreak.