5.15.7 is the latest version, so it won't show you the option to update to 5.15.7 64 bits as it currently only allows changing to 64 bits if it is a version above. You can try downgrading to an older version and then update it to the 5.15.7 64 bits.
5.15.7 is the latest version, so it won't show you the option to update to 5.15.7 64 bits as it currently only allows changing to 64 bits if it is a version above. You can try downgrading to an older version and then update it to the 5.15.7 64 bits.