The thing that makes this tricky: In Portuguese we're constantly reminding you to make sure to get your gender straight. And I'm not talking about your sexual preference here não! It's a constant struggle to keep word gender correct, certo?
Muito or Muita?
Minha cerveja está gelada.
Meu vinho está gelado.
We're going to use all-alcoholic examples in this post. Warning.
What happens when you add a very to the, cold? : very cold --> muito or muita gelado/a?
Answer: always use muito.
This seems to go against what you've learned about gender agreement! The explanation for this comes down to the agreement rules for adverbs versus adjectives, but for practical purposes, all you need to remember is this:
When talking about degree (very), always use muito.
When talking about quantity (a lot of), use muito or muita as needed to agree with the thing you're talking about.
A deeper dive into the grammar of using muito or muita can be found here.