Hello,
Thank you for posting to Apple Support Communities.
If you're unable to change your iCloud storage to 50GB, you can check to see if your content exceeds the amount of storage needed. Here's how to check this:
- Tap Settings > [your name] > iCloud > Manage Storage.
- Select Backups.
- Select your device name.
- At the top of the screen, you can see the information about the Backup Size.
- Tap Show All Apps. You will see a list of your apps and how much data is backed up to iCloud.
This information is provided in Manage your iCloud storage.
If those steps don’t help, we’ll need some additional information to provide more specific support.
Do you have Family Sharing set up?
Are you signed in with the correct Apple ID you use with iCloud?
Take care.