Hello and welcome! Congratulations on your new additions.
I suspect (correct me if I'm wrong) that you got them from a pet store of some kind? I say that because sometimes the smaller species - finches, budgies/parakeets, etc. often times come from pet stores with a fear of hands/people. If they were in the same cage together at the pet store when you picked them out, that means they have probably been friends for some time, and therefore have relied on each other for that companionship birds want. Sometimes in a situation like this, they will not accept a human owner and only bond to each other.
There are ways to combat this and earn their trust, but know that it may be a long journey -- not impossible -- but will require lots of time and patience.
This is a great thread for beginners --
Tips for Bonding and Building Trust . Remember that birds have no reason to trust people, so we much teach them that only good things happen when people are around. It sounds like you need to press the restart button on your relationship with your new birds and begin from square one -- getting the two both comfortable with your presence.
Before attempting to offer them millet, sit near their cage, doing something that isn't including them - reading, crafts, etc. The idea is, you want them to get used to your presence so they no longer fear you approaching them. This may take a while, days, weeks, months, but eventually you work your way up to putting your hand in the cage with treats, millet, and allowing them to climb all over you. After you've reached that point, you move on to 'step up' training, which is asking each bird to step up onto your hand. Eventually you will then be able to let them out of the cage and work on recall, training them to fly to you!
Patience, love, and understanding is key! I hope this post has been helpful to you.