Is icloud password the same on all devices?

You use an AppleID to access your iCloud account. On all devices using the same iCloud account, the AppleID used and it’s password will be the same.

If your Mac is different, then it is using a different iCloud account. Log out of that account and log back in with the AppleID you’re using on all the other devices.

Is the Mac logged into iCloud using the same Apple ID as the one used on the devices? You can change the Mac to the same Apple ID, but you risk losing some of the data the Mac has stored in iCloud if you do that.

See Winston Churchill's response in the below discussion. Also set up Family Sharing to keep access to your apps/purchases. 

How to transfer all files from one iCloud account to another

 Apple ID email address or password - What to do after you change

Family Sharing

Family Sharing - Set up