It is not possible to solve a standard Rubik’s Cube in only 4 moves from every scrambled position.
If the cube is already nearly solved, use the exact 4 moves needed for that specific position.
For a full solve, use a standard beginner method:
Solve the white cross
Solve the white corners
Solve the middle layer edges
Solve the yellow cross
Orient the yellow corners
Permute the last layer pieces