The file you're looking for is Accelerators.XML 

Mac or PC?

On PC just choose the option to "Keep existing preferences" during install.

Macs don't really have an installer so it can't preserve preferences. You'll need to copy the prefs folder back each time.

Any time you update or reinstall the previous presets are backed up (Unless you choose to delete them) You can copy the previous preferences back by simply renaming the backup folder.

On PC it's in %appdata%\Poser\

On Mac it's ~/Library/Application Support/Poser/

The "13" folder is the current preferences. 13 followed by a date and time are backups from previous installs. Rename the current 13 folder to 13 backup then rename the one with the newest date stamp to be 13