Elle a des opinions bien arrêtées en politique.
Don't be so opinionated about other people's choices.
Example: She has a strong opinion on that subject.
Translation: Elle a une opinion bien arrêtée sur ce sujet.
to voice one's opinion
Example: He always voices his opinion at meetings.
Translation: Il exprime toujours son opinion lors des réunions.
to be set in one's ways
Example: My grandfather is very set in his ways.
Translation: Mon grand-père est très borné.
to take a stand