Some image programs display photos that have been taken sideways correctly but that doesn't mean they will show correctly in all programs or on the internet. The easiest way to see if they are positioned the way you want is to open the folder they are in, right click inside the folder, (not on a file) and select view large icons. From there you can see which if any files are embedded to display sideways. Then simply select the files that are sideways, right click, and select rotate clockwise or rotate counterclockwise. Windows will fix it and it doesn't require you to save anything. If you have several files in a row that are sidways you can select the first one, hold down the shift key, and use the arrow keys to select all the photos you want to fix and do them all at once.