Custom presets for declining calls

[CPD]

When declining a call, you have the option to type a custom message or use one of the preset messages. I would love to use the presets more often instead of writing a custom message every time, but out of three messages (in German), one translation is incorrect (missing a word) and one does not fit my professional context (using the formal "Sie" pronoun). Is there a way to modify these presets?