Windows Live Mail spell checking – how do I change the automatic spellings?

I'm using English (UK) as default language.  Somehow, a few of the default spellings have been changed, and I can find no way to modify them.  An example, i often type "i" when I mean to type a capital "i", and then have to go through the message and correct each one individually, as they are not picked up.

Can I change the default spellings so that it highlights this, or automatically changes them? 

Also, when I type my christian name without a capital letter it does not highlight this. Same issue, I'm sure.

Can I make any changes to default spellings, and if so how?

Thanks.

K