windows file sharing user checkbox issue
I have a new Macbook Air, and am wanting to complete the 'file sharing' process to include Windows File Sharing but when I go to 'options' after turning file sharing 'on', the checkbox next to my name that I should select to turn 'on' is unselectable - nothing happens when I click on it so I cannot set up a password for the other computer to complete sharing.
Can anybody help? I am new to the Mac world but think I have followed all the steps I have found to enable printer and file sharing process, and the windows computer can see me, just cannot connect until I can complete the password part on the Mac
I am running yosemite 10.10.5
iPhone 6, iOS 8.1