Safari passwords and migration to new mac
After setting my account in a new iMac (High Sierra) with Migration Assistant, I have found that some, but not all, passwords stored in Safari have been moved ok. I thought that Safari data are stored in keychain and while I can find my keychain data (passwords, certificates, notes and even ssh keys) in the new mac, some Safari passwords are missing. I wonder where are actually stored and how can be selected and exported either to a keychain or at least to a text file. Migrating again the account is not an option. I don't use iCloud for password and I don't want to either...
Thanks for your help
F.J. Modrego
MacBook Air, OS X El Capitan (10.11.6)