The main reason for this type of issue to occur is the orientation the file is saved in that you trying to upload.
E.G. if using a mobile and you take a photo upside down (camera at the bottom) the phone will detect this and auto rotate it to display it to you the right way up. However it saves the image in the original orientation it was taken in. The best way to solve this is to transfer the image to a laptop/desktop and:
Open the images in a system that can allow you to edit the image
Find the option to rotate it and rotate it to the correct orientation
Save it
Now upload it on Bluethumb (or any other site)
You may want to to also check the operating system you are using on your devise is the most recent update, and we strongly recommend using Google Chrome where possible on site for any photo related work (its the best).
Alternatively you may need to retake the images in the correct orientation you want them to be displayed in if you are unable to access editing software.