Use 'Create WinRAR.ini file' command in 'Import/Export' submenu to create a new WinRAR.ini file and copy existing WinRAR settings from Registry to this file. WinRAR searchs for this file first in its own folder and next in %APPDATA%\WinRAR.
If you create an empty WinRAR.ini file either in the same folder as WinRAR.exe or in %APPDATA%\WinRAR folder, WinRAR will redirect access to HKEY_CURRENT_USER\Software\WinRAR and HKEY_LOCAL_MACHINE\Software\WinRAR Registry keys to this file.
It is possible to redirect WinRAR Registry access to text file. But if you plan to install WinRAR on removable media, such as USB flash drive, and then run it on different computers occasionally, you may prefer to avoid storing any WinRAR specific data in Registry on those computers. Such approach is reasonable when WinRAR is installed and used on the same single computer. By default WinRAR stores settings in Registry.