That happens because the library location has moved since the last time the callers VIs have been saved.
To begin with, in the LabVIEW options, under Path/VI Seach paths, add an entry to the current location of your library. The next time you will load the callers VIs, that location will be searched before looking the whole hard drive. When all VIs are correctly linked, save all your VIs. Once the callers are saved with their subVIs at their correct location, the subVIs won't be searched again.
Another way is to load in memory all current subVIs before loading the callers. The callers will link to the VIs version in memory first. Again save all VIs.