Changing Joomla Messages
One of the frequent questions in the Joomla forums has to be: "How do I change the following text:?" in Joomla? Well, basically Joomla uses a set of files to display the default text messages (i.e. besides the articles which are found in the sample content or any articles which you enter yourself). Joomla can make use of any language, as long as the translated text files have been installed via the Extension Manager (Extensions > Install).
Create your own messages
Once the language has been installed, you can then change any text, by accessing these files and changing the text found in the different files in the language pack files e.g. you want to change the text: "You have successfully logged in", to "Welcome to the members section of our website", you simply find en-gb.ini file (located in language/en-GB/ folder and change the text:
LOGIN_SUCCESS=You have successfully logged in.
LOGIN_SUCCESS=Welcome to the members section of our website.
Make sure you leave the part before the equals sign ( = ) identical. Never change that, because that is used to choose which message will be displayed. Also if there any percentage signs, those are termed placeholders for some text. You should keep them in the new text message, and ideally the same sentence structure.
SEND_MSG=Hello %s,\n\nThank you for registering at %s.\n\nYou may now log in to %s using the username and password you registered with.
SEND_MSG=Greetings %s,\n\nWe appreciate you registering to become a member at %s.\n\nYou may now log in to %s using the username and password you registered with.