More to the point, the source tarball (if you downloaded from www.OpenSSH.org
) always installs to the same place, but if the original system came with OpenSSH or had it installed as a package, it could be in a different place. If the old OpenSSH is in a directory that's in your path before the directory where the newly built OpenSSH was installed, that's why you're still getting the old one.
This is why it is generally not advisable to compile software from source. You should use pre-packaged software for your own OS if at all possible. If a new version is not available in package format, then you should change the ./configure arguments to make the prefix for your source build point to the same prefix where the older binaries are installed, that way they will be overwritten.
PS, generally when you install a new version of OpenSSH it also requires a new version of OpenSSL to be built and/or installed as well.