How to change wording on error messages shown to user?

[Don]

Hello

It’s possible to setup a prefilled category. When users open composer this category will be selected by default.

default composer category site setting.

@jomaxro

New site setting: default composer category

Admins can now configure the default category for the composer. The selected category will be pre-filled in the new topic composer. The setting applies when starting a topic from pages other than a category list. If creating a new topic while browsing a specific category, for example bug - Discourse Meta , the composer will pre-fill the category being viewed.