Add an "Edit in Composer" button to your toolbar. That's all.
There is no change in my toolbar!
This additional button is shown when a current page's type is included in Composer. Please check your site's settings of the Page Type.
If you don't have permission to access to Composer page in Dashboard, or you can't edit the properties of the current page, you can't use this button. Please check your site's settings of Permissions.