Beyond Compare stores your sessions, customized file formats and other preferences as .xml files in its settings folder. A quick way of finding this location is to pick Help > Support and click the Explore settings folder link at the bottom of the dialog.
Standard installation
In Windows, the settings folder is inside your Application Data folder. The location depends on your version of Windows. For instance, under Windows Vista the settings folder is:
C:\Users\<username>\AppData\Roaming\Scooter Software\Beyond Compare 4
Notice that this location differs for different users on the same computer.
In Mac, the settings folder is:
~/Library/Application Support/Beyond Compare
If you want to install multiple major versions, you can rename this folder to:
~/Library/Application Support/Beyond Compare 4
In Linux, the settings folder is:
~/$XDG_CONFIG_HOME/bcompare
If $XDG_CONFIG_HOME is not defined, the settings folder is:
~/.config/bcompare
If an older version of Beyond Compare has been installed, the settings folder is:
~/.beyondcompare
If you want to install multiple major versions, you can append the major version to the settings folder name like this:
~/$XDG_CONFIG_HOME/bcompare4
Portable installation
If you prefer a more portable installation with the program and settings all in one location, you can copy your settings files to the same folder as the program. Portable installs allow you to share one set of settings for all users on a computer, or take your settings with you. If you don't have existing settings files to copy, you can create an empty file named BCState.xml in the folder.