Set a home ground address at club level and every team will use it by default. This is handy when all your teams share one pitch. If a particular team plays elsewhere, you can give that team its own ground address, which overrides the club-wide default just for them.
Either address can also be overridden on a single fixture when needed. A one-off away day or a neutral cup venue doesn't require changing anyone's regular settings. See Creating and editing fixtures.