When you create a homegroup, a password is automatically assigned, but you can change it later.
Open HomeGroup by clicking the Start button , clicking Control Panel, typing homegroup in the search box, and then clicking HomeGroup.
Click Change the password, and then click Change the password.
Type the new password you want to use (or accept the suggested one), click Next, and then click Finish.
After you change the password, everyone connected to your homegroup will be asked to enter the new password.