editing addresses in Office mailings

I have an Excel file of addresses and an envelope referring to it. I want to make some of the lines bold or of a larger font, and do not see at all how I can do that. I also want to put the postcode on the same line as the country.

I would also like to be able to use the same envelope file with another Excel file in the same format as the first without having to mention whether I want the company name, etc.