Cannot open exported JPEGs - unidentified developer

When I export an image from Illustrator and double click the exported image, it defaults to opening with Preview. I'll then right click and use "open with", then select Photoshop as the app and "always open with", however, when I then double click the image, it gives me the same message you'd receive from an app that is from an unidentified delevoper, but this is a JPEG image. I'll then click "open anyway" and it opens in Photoshop, but anytime I export any new image, it treats it like another new app from an unidentified developer. It does this for literally any image I export. I've never had this problem before updating to High Sierra.

Is there a way to get my mac to no longer treat any and all images I export as being from an unidentified developer?

Thank you for your time.

iMac 27-inch, Late 2013

3.4 GHz Intel Core i5

8 GB 1600 MHz DDR3

MacOS High Sierra

Adobe CC (Photoshop and Illustrator)