Sometimes, once you have create VBA, you need to put a password, so, it will be unvisible by other.
Hereunder the step.
1. From your excell sheet, got to VBA Editor, or just press 'ALT+F11"
2. Click on Tools and find "VBA Project Properties"
3. Click on "Protection TAB and chek "Lock Project from Viewing", and set your password,