Although Linux and Mac OS X were 64-bit versions a few years ago, and Mozilla had previously planned to abandon the project, the team broke the 64-bit version in November 2012. In 2014, Mozilla announced the restart of the 64-bit Firefox program; early 2015, 64-bit version appeared development channel: November 3, 2015, Mozilla released Firefox 42.0 official version of the first 64-bit version.
According to the official description, the current Windows system to obtain 64-bit Firefox in two ways
1. Download and reinstall from the official website of Firefox , the default will be installed Firefox 64-bit version
2. Wait: Migrate existing 64-bit Windows users using 64-bit Firefox in future version updates. If consumers prefer to use the 32-bit version after the migration, consumers can download and return to the 32-bit version via the Firefox platform and language download page .
