Boolean difference modifier merges two object i want to use difference in Boolean modifier but actually the result are like it is merged, i want a hole inside a custom shape. beore using difference:


and here is the result after difference is applied, it is like the cylinder is merged instead of subtract:


i have tried this link suggestions:
Using difference modifier on two objects doesn&#39;t always work

i am a total beginner so if i am making a stupid mistake please accept my appologies.
You need to have consistent normals on your objects - normals determine what is outside and what is inside.

To recalculate normals go into Edit mode (Tab), select all geometry (A) and perform "Recalculate normals outside" (Ctrl+ N)

After all your pieces have correct normals (you will also notice consistent shading of all objects) - booleans will work as expected.

You might also want to set the object that you do boolean with as wireframe (you do that under Object Display options):