How to change the word "blog" for "journal"
There is String Overrides module.

Provides a quick and easy way to replace any text on the site.

Features
Easily replace anything that's passed through t()
Locale support, allowing you to override strings in any language
Ability to import/export *.po files, for easy migration from the Locale module
Note that this is not a replacement to Locale as having thousands of overrides can cause more pain then benefit. Use this only if you need a few easy text changes.