Photoshop is (appropriately and necessarily) a color-managed work environment. The photos you posted here have embedded ICC profiles that reference the sRGB color space. To view the photos correctly the software you use to display them must read and process the embedded profile and display the photo correctly relative to its referenced color space.
If you re-open a saved photo in Photoshop it should look exactly as it did before you saved it. I assume that's the case. You experience a difference in the appearance of the photo when you see it displayed using some other software, for example Microsoft's Internet Explorer web browser. That other software isn't doing the required job of processing the photo's embedded profile. This is a fairly common problem. It has an easy solution once you know what's going on: Don't use bad software. What software is bad? Any software that displays your photo differently than Photoshop would qualify.
Unfortunately you can't prevent other people from using bad software (or creating it for that matter). Can't help with that one.
JPEG files from your camera will have an embedded profile that identifies the reference color space. If your camera allows you a choice it will likely be between sRGB, Adobe RGB and/or Pro Photo RGB. Unless you have a clear understanding of what those are, chose sRGB.
Under the Edit menu in Photoshop select Color Settings. Select the option North America General Purpose 2 and Photoshop will default to sRGB. Your good to go; now avoid bad software.
Take Care,
Joe