apologies, if this is an RTFM question - any pointer to the right section in the manual is appreciated, too

When users are running RemoteApp via the web portal they get some default settings - where do we actually change those settings? We tried generating a remote app client and replacing the original Clients\www\RemoteAppClient\Setup-RemoteAppClient.exe with no success. Apparently, our settings are not effective and probably the setup exe is only downloaded and executed the very first time a user connects, anyway(?).
Any hints appreciated ...
Kind regards,
Tom