I am not an administrator on this machine. Therefore, I am unable to save the path in 'pathdef.m' in its default location (as I do not have write privileges in the installation folders).
Thus, I have saved pathdef.m in another folder which is on my path. Now, I add more directories to the MATLAB path and save it. I can see that pathdef.m is updated and it contains the new paths. However, when I quit MATLAB and restart it, MATLAB restores to the default MATLAB path and it does not recognize the folders that I recently added. I have to add these folders to the path again.