Tweaking default text strings (but not translating)

I’ve searched for info on this but every search returns a haystack rather than a needle, so it has not been productive.

I don’t want to “translate” strings to a different language, I just want to modify what subscribers see so that I’m referring to “me” and “I” rather than “us” and “we” (and similar tweaks). I’m an indie author keeping in touch with readers, this is clearly a one-person business, so making it sound like I’m a group of people is bad form. An example is the replacement text for the [CONTACT] placeholder.

I see the .inc files in public_html/lists/texts – is that the right place to change these values? If so, this is too easy to forget to save in a later upgrade, so changes could easily be lost. I was expecting to find something in the database, and maybe something in the UI to change that, but the only strings I’m finding there are in the i18n table which seem to be specific to the admin interface (?).