When I'm saving settings in context of process runas with specific login and password it's using his home folder (AppData) to store settings. But if I run program in context of the same user from T-SQL Trigger settings file form app_data is not used. There is config file which is used. It's placed in program files with executable. In this config are sections for WCF client settings.
I'm wonder why program doesn't try to read first config file. After manually putting some values to the user section in config when program is running from trigger - he will use them. But for save form single instance it store them in AppData. So after all, when running from trigger in default scenario he reads empty values.
BTW For running program in context of user from trigger I use EXECUTE AS USER = ... exec master..xp_cmdshell ... .
Best Regards