They are cute as!!! Congratulations I have to agree with Kaz about the seed... do NOT remove it, gradually or anything. They will starve and die. Instead introduce some veggies etc... and sprinkle some seed on it, as suggested... but do not remove their seed bowl. Getting them to eat different foods can take time but that's okay. You can also experiment by clipping some bok choy or other dark green leafy stuff (not lettuce) to the sides of the cage. They may be interested in nibbling on it. Also agree on stopping or only using occasionally the sticks, as they contain lots of sugar.
The behavior of climbing into the seed dish is also normal at that age. Again congrats!