The app itself automatically selects the last used profile on next application start. There is no option to force a specific profile.
This could be enough for (most of...) our users.
Just another question: I noticed the profiles are saved in the HKEY_CURRENT_USER registry key, so they are related to a single user.
Since we install PDF24 silently (we use WPKG, with some adaptation from this approach) we don't know what is the dominant PC user. Aren't those keys installable system-wide (such in HKEY_LOCAL_MACHINE or similar)?