Relationship behavior disabled in 1:N Relationship

Hi everyone,

When the account owner changes the owner of the activities associated with it also changes.

I have a requirement to retain the owner of the activity even if the account owner changes.

However, when I go to the Relationship Behaviour under the 1:N relationship of the activity the options are disabled.

Is there any work around to avoid changing the Activity owner name when the account owner is changed?

Any links or ways to achieve this would be appreciated.

Thanks in advance!