Hi Fiona,

I just ran through this myself, it's a long path, but not too many twists:

Log in to your totara, and find the adminstration block,

expand 'language' option, and click 'language customisation'

In the dropdown box choose the language you want to edit,

Then on the page that loads click "Open language pack for editing"

(wait)

....

Click continue.

On the page that loads you need to enter some settings to find the 'language string' that you wish to change.

For your case in the components box you want to select "moodle.php" under core, although you can select multiple if you don't know where you need to look. Put "new account" in the option 'Only strings containing' option.

Click "Show strings"

A collection of strings will come up showing what the standard text is, and the value you have now.  Find the one which relates to the emails that get sent out, and hopefully you can see what you want to change. Where you see "{$a->firstname}" that's a placeholder that totara will substitute with the user's name before it's sent out. If firstname is used in the standard string, then it's safe to use it in your custom string, but if you want to use something that isn't in the standard string it's worth testing to make sure it's available before trying to use it on your prod site.

Hope that helps.

Peter