On budgie changing cere color....
What color was the blue? Light blue or royal blue? If it was light blue, then it was a female in the first place. If it turns brown it just means she's getting hormonal.
My budgie's cere constantly changed from light blue to brown, but it finally settled at light blue for a while, and then slowly turned brown again, and it will probably turn back to light blue soon. I didn't realize light blue could mean female until like, last week lol
I thought she was sick too or changing genders until I realized this
On getting birds to try pellets.....
Have you tried Zupreem's fruity pellet mix?
https://www.zupreem.com/products/birds/ ... all-birds/Many people use this when switching their birds from seed to pellet. It's very popular, birds really like the fruit flavor. I would suggest getting the one for very small birds, same nutritional value, just different size. It'll be easier for them to eat.
As for getting them to change in general, here is a trick I've heard but never tried:
Take the pellets and put them in hot water, and then press them down on the seed. They will work hard at the pellet to get to the seed, but then also get a taste of the pellets! Don't give it to them hot though but I think you know that. Start small at first with this trick, then slowly increase the pellets.