keychain on MAC

My keychains on my iPhone, iPad and iPod appear to have the same information in my keychains. But several are missing on my MAC. I'm not sure how many. Keychain is turned on in iCloud on all my devices. What to do besides typing them all in. Could I have a setting wrong on my MAC? Thanks for any assistance. All OS are up to date. iOS 15 on iPhone, iOS 12 on iPad and iPod and Monterey on the MAC