rewrite email sentences .mo and .po files

Hello tech support,

please inform how to update proof – rewrite the hard coded sentences in the .po en .mo files.

For my store, i don’t want to speak to my customers as “Je”
It is more polite to speak to my customers in a “U” form..

(I use a child theme, so there is room for subfolders and also a functions.php)

Thank u for your help,

Best A