Serato DJ Pro supports high resolution displays. Ensure the 'Hi-Res Screen Display' option is enabled under Setup --> Library + Display:

Enabling this option will place a higher overhead on your system performance, and may cause issues with lower spec'd computers. You will need to restart Serato DJ Pro after enabling this option before it takes effect.

Below are some further options if you choose not to use the 'Hi-Res Screen Display' option, although it is recommended.

OS X (Mac)

1. Open System Preferences and click on "Displays".
2. Make sure the "Display" tab is selected and click on "Scaled" for resolution.
3. Click on the "Larger Text" option to increase the size of elements on your screen - this should make Serato DJ easier to use on high definition screens.

WINDOWS (PC)

There are two seperate options to change screen size in Windows, DPI and Resolution. You will need to adjust both the resolution and DPI independently (find a balance depending on your display) to achieve a good size for use with Serato DJ.

To adjust the DPI:

1. Right click on your Desktop and select "Display Settings".
2. Adjust the slider to change the size of text, apps and other items (try a higher scaling percentage to increase the size, eg. 300% looks good on 4K displays)
   

To adjust resolution:

1. Open the control panel and select "small icons" from the view panel. You will now see all your control panel items.
2. Click "Displays"
3. On the left hand side menu bar, select "Adjust Resolution".
4. You can now choose an appropriate resolution for Serato DJ. Use these options in conjunction with the DPI scaling to find the best resolution for you.