Please can you show difference between the kids want to (plural) and... The kid wants to (singular). Thanks!
"The kid wants to" = "Đứa trẻ muốn" and "The kids want to" = "Những đứa trẻ muốn"
Tôi vĩnh viễn muon ăn phở bởi vì nó rat ngon!
"vĩnh viễn" is "always", with the meaning of eternally, forever. I'd rather suggest you use "luôn", also "always" but like in all the time.