"Explorers, Wallets and Marketplaces, MUST CHECK that Verified is true. Verified can only be set true if the Authority on the Collection NFT has run the VerifyCollection instruction over the NFT."
To do this you need to add a property collection to MetadataAccount
As written in the Metaplex documentation:
To do this you need to add a property
collection
toMetadataAccount
Certified collections documentation