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There is a lot of Workflow video in youtube. All the videos regarding SharePoint Workflow I can find are using static account for approval. I found an article post on creating dynamic approval by the manager of the login user and I have also refined the steps and posted it to https://chanmingman.wordpress.com/2016/01/01/create-an-approve-by-manager-workflow-in-sharepoint-2013/. The post did not include how you test the workflow that you have created but the video did.
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