I just got a new laptop and installed Photoshop. I am used to using it so I know how the right size of my images should be. But now when I upload an image in expamle 1080p it looks two sizes smaller than it actually is. Now when I want to change the image size I will type in 500p, but it will only look like 250p. How can this be? I never had this problem on my other laptop? (and also I have checked that it is in 100% when it does this). Please can someone help me quick, I need it for a really important thing for work.
1080p is a HDTV thing images are 1920px by 1080px. There is also 720p where images are 1280px by 720px. Both have a 16:9 aspect ratio. 1080p images will be scaled to 1280x720 on 720P HDTV and 720p video will be scaled to 1920x1080 on 1080p HDTV sets. Photoshop video rendering has both 1080p and 720p presets. Photoshop Images size does not. Also when you resize image using Image Size you want to constrain the resize aspect ratio if you do not the image will distort.
What are you actually trying to do? I think you may have a new laptop with a high resolution display. High resolution displays have a high DPI resolution and display many more pixels then low resolution displays the same display size. Displays use their DPI (PPI) resolution not the image print DPI resolution. Images with the same number of pixels look smaller on high dpi resolution display then on low dpi resolution displays because of the difference in the displays pixel size.
Most Desktop displays have a low PPI in the area of 100DPI. There was a 204PPI 22.2" display IBM made it displayed 3840x2400 pixels back in 2001 no longer available. Even new Desktops 4K displays have a low resolution like 180DPI because of their large size 30"+. New laptops and tablets can have high resolution some over 300PPI and will display 2560x1600 pixels or more on a small screen like 10.1".