date created displays incorrectly

I have saved tons of video files in dropbox that I had previously taken off of my iphone to save space. (also backed up on an external) I have since signed up for icloud Photos and would like to put the old video files back into my icloud photos library so I can easily access them on my phone in a visual way that I prefer. That's easy enough to do by dragging from dropbox into Photos on my desktop. However, I noticed when I do this it doesn't put the video in proper chronological order. The date dropbox has saved as "date created" is the date I uploaded it to dropbox instead of the date the video was actually taken. Thankfully, the true "date created" still exists in the data when I look at the same file on dropbox via a browser. How can I get dropbox to recognize the proper creation date when viewing on my desktop so that I can import the videos in correct chronological order into Photos?