This is adjustable - sorry for UI in French - https://imgur.com/a/Rn046lL

For a password saved from foo.contoso.com:

First option - "Fill anywhere on site" - this means it will fill on foo.contoso.com and bar.contoso.com

Second option - "Fill only on the specified hostname" - will only fill on foo.contoso.com

Third option "Never fill" - written on the tin.