Root user cannot change S3 bucket policy

Hi,

I have created a new S3 bucket and am following this tutorial to host a static website: https://docs.aws.amazon.com/AmazonS3/latest/userguide/HostingWebsiteOnS3Setup.html#step3-edit-block-public-access

However when it comes to setting the bucket policy, it states that the root user has no access to manage bucket policy. I then went to the IAM console and gave another user S3FullAccess. This still does not help and there is no access available?