Need help: breast milk to formula 😓

Britt 🌲
My baby is almost 8 months old and I'm trying to wean and transition him to formula. We supplemented within months 1 & 2, and he had no problems drinking formula back then. Today I had him try several kinds of formula and he made a "yuck" face each time and fussed. This is really hard for me. How can I make this transition easier? 😰
*Also, he has been bottle fed since the beginning because I exclusively pumped. So that part will be easy.