How do I get my budgies to eat more seed?

My budgies are obsessed with millet seed and they eat almost all of it in a day (three male budgies) but the seed I put out almost a week ago seems almost untouched. How do I get the budgies to eat more seed and ration the millet seed? Should I take the millet seed out? I need a lot of details, and if you're a ve I would greatly appreciate your help.