To enable softswitching on your XDJ, you need to open the settings menu and find the softswitching option. Here are the steps to follow:

Turn on the XDJ and go to the settings menu.

Look for a "soft takeover" option. It may be in a submenu such as "controller" or "mixer".

Once you find the "soft absorption" option, select it and turn it on.

Save changes and exit the settings menu.