On another thread "This is driving me Mad" I posed that sort of question.
I have two almost identical computers which have PDFC 2.5.1 installed on them, both updated from previous versions.
On one machine I only get to see the config pane if I call for it, on the other machine as you note, that pane becomes a Pain that presents every time a PDFC printing is required.
Some suggestions were offered on the thread, but did not make any difference to the Pain of the config pane.
In the end I applied an old, well tried and tested method for recalcitrant applications.
I used Revo Uninstaller to uninstall PDFC everything, the app, the configs, and the registry entries.
Then I reinstalled PDFC 2.5.1 from scratch and the config pane is no longer a Pain.