1. Them are the juiciest oranges that I have ever eaten.

I have to replace incorrect pronoun with correct pronoun.

1. Replace I with we

How can you speak for others? "I" is the correct pronoun.

Please look again to find the pronoun that should be a subject, not an object pronoun.

They

Right.

To replace the pronoun "I" with the correct pronoun "we" in the sentence "Them are the juiciest oranges that I have ever eaten," you would need to revise it as follows:

"They are the juiciest oranges that we have ever eaten."