Hello Kerim,
If you want to change the the text of the link 'Create Travel Expense Report' in Transaction 'TRIP' you have to change the textelements in program SAPMP56T.
If you call transaction se38 program sapmp56t, textelements- search for element A32
'Create Expense Report'- it will be converted in html and works as a hyperlink in transaction trip.
But a change will aslo have influence to other transactions- like PR05. In the menu your new text will also appear.
BR
Klaus