Hi Ruben,
from knowledge this is hard coded.
The system "stores" the last employee selection and try to open with this PR05 data and also TRIP.
You need to change via the icon Richard has shown to you.
If you just implementing TRIP please be carefully because this transaction is a little bit out of time.
No further developments planned by SAP but of course support of current functionality.
What do you like to build here? Have you thought about using WebDynpro for ABAP (this works even without Portal set up - only some parts of navigation will not work - like "what do you like to do next")
Best regards,
Sigi