Check whether your 75% keyboard has RGB or single-color backlighting
Find the keyboard’s lighting shortcut keys in the manual or on the keycaps
Press the lighting function key plus the assigned key to cycle colors
Use the keyboard’s dedicated software if it has one
Open the software and select the lighting or RGB settings tab
Choose a preset color, effect, or custom color
Save or apply the changes
If the keyboard uses onboard controls, try common shortcuts like Fn plus arrow keys, Fn plus spacebar, or Fn plus a function key
Update the keyboard firmware or software if lighting controls are not working
Reset the keyboard to factory settings if needed