I am trying to downgrade my iCloud storage plan. I have followed the steps of Apple Support HT201318 for OS X. When I try to enter my password, it is not accepted (no message, just resets). Yes, my password is correct.

Hey There saaymast,

The resource below will explain how to manage your iCloud Storage. Are you using the same Apple ID for iCloud as you do for iTunes? If your issues is still not resovled after following these steps, there is a link to the iCloud Support team. With your permission, they will be able to look into the details of your account and help you change the plan.

Get help using iCloud storage - Apple Support
https://support.apple.com/en-us/HT203527

Make sure that you're signed in to iCloud with the correct Apple ID

Use these steps to check your Apple ID:

• iPhone, iPad, or iPod touch: Tap Settings > iCloud and tap your name.
• Mac: Choose Apple menu > System Preferences > iCloud > Account Details.

If you still can't downgrade your storage, contact iCloud Support.

Hope that helps ...

- Judy

Mine is doing the same did you find out how to do it.

Contact iCloud support using the above link.