KeepNote Portable settings Helper applications

Hello

I have installed KeepNote on my PortableApps Stick. In the settings of KeepNote there is a section Helper Applications, where you can set the path to applications like your browser, your file manager, etc.

I can set absolut paths, starting with a drivew letter D:\... But when I use the stick at another windows host the drive letter may chance.
I tried relative paths, but I always get errors (application could not be found).

Has somebody managed to use PortableApps applications as Helper Applications?

Kind regards, jandoe