If you have at some point edited a setting, such as the growth rate, for an account at the account level -- in the Advanced Settings > Growth panel -- this will override the default preference going forward. Any future changes that you make to default growth preferences will not affect the growth rate for that particular account.
If you have at some point edited the growth rate at the account level and want to revert the account back to use of the default growth rate, open Advanced Settings > Growth, select and clear the Growth Rate % field (leaving it null). Click OK and Update to save your changes. This will clear the edited growth rate, which will then be replaced by the original default growth rate.