And can whatever genius answers that, please please tell me how to keep the stupid program spell-checking in English (UK) and not English (US)? It's driving me nuts. I keep changing the default and it keeps on going back to US.
It's SO much easier to troubleshoot when you say what version of Word you have, you know.
Nonetheless, to attempt to answer your question:
In
Word2007, it'll be Office Symbol--> Word Options (all the way at the bottom of the menu). The first menu on the left is Popular. This includes the button for Language Settings.
In
Word2003 it's Tools--> Language--> Set Language. If you already have text in the document, you will have to select all the text (Ctrl+A) and then set the language to your preferred form. Otherwise it tends to not keep the language setting. (Your problem makes me think you have 2003 or earlier, but this is a thread about 2007...?)
It's not a universal setting, but rather per doc in many cases.
It may be useful to uncheck the "detect language automatically" box, too.