Thank you for your post.
The reason it is not changin for them is that the information is stored in the ini file and unless you are logged in as an administrator then it cannot access this file to save these settings.
To get two seperate installations simply run the installation twice and save it in different directories each time. This way you can link to two seperate executables - one for one instrument and one for the other.
You may also like to download the latest software as this is much newer than the version you have. You can get it from www.picotech.com/software
Hope this helps