Microsoft recommends the C:\Program Files for default installation destination. It’s a convention that ensures proper inter-operation between your program and the OS’s application and security models. So, once software programs are installed they go by default to C:\Program files on the computer.

This can however be changed by selecting another folder or location or partition.  To change the default installation folder, the data must be modified in the ProgramFilesDir key and a new path must be chosen for the installation folder.

Windows uses the System Disk for installing any new applications, That is, if your Windows is installed on the C Drive, the default folder where all the applications you install would automatically show up as C:\Program Files, unless of course you change in manually while installing the application’s locations.

Change default Program Files directory

If you almost always prefer to NOT install on the System Disk, but instead on another partition, say, the D drive, then rather than changing the default location every time, you can edit the registry as follows:

Open Regedit and navigate to the following key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion