The photos you are editing can be saved in image format which are compatible with applications you are trying to open them in i.e. jpeg, png etc. You must be saving them in PSD format which is Photoshop Elements compatible and can't be opened in some applications.
For saving files in different formats, please see Save images in Photoshop Elements
To save these files as individual files, you need to uncheck "Save in version set" option on Save As dialog while saving in Editor.
For existing version sets to convert to individual files in Elements Organizer, please refer to this help guide: Grouping photos in version sets in Elements Organizer