Generally, according to the article below, the subsites will inherit the theme from the parent site. Here is the article link: http://office.microsoft.com/en-us/office365-sharepoint-online-enterprise-help/choose-a-theme-for-your-publishing-site-HA102891580.aspx If subsite is from another template, then follow the instruction below: 1) Since the link of Master page setting is hidden, you can change the URL to the setting page by two steps. Copy your site URL and remove the target of URL after the default URL. See the example below: Root URL : https://XXX.sharepoint.com/SitePages/Home.aspx Change to : https://XXX.sharepoint.com/ Add the ‘_layouts/15/ChangeSiteMasterPage.aspx’ behind the URL from step a. See the […]