Public displays showing static content such as news and advertisement are very common, but are often ignored of users expecting them to show uninteresting content. Although applications showing dynamic content which could reduce the display blindness exist, distribution channels and concepts for successfully moderating user-generated content on public displays are still missing. We developed an app store for public displays and analyzed six potential moderation strategies for, in particular, user-generated content. To do this, we conducted an online survey. Survey participants mostly specified that content moderation is necessary and preferred a reactive moderation strategy. Moreover, they expected their messages to appear instantly. Therefore, we developed the UniDisplay application and did an in-the-wild-deployment to investigate the impacts of moderation delays on user behavior. We conducted data and content analyses, observations, a survey and interviews with users of our application. Hence, we can show that already a short delay time of messages (90 seconds) may confuse users and that the delay time is not the only strong factor for posting to a display. On this basis, we built a theoretical concept for integrating content moderation in public display app stores. In the long term, understanding the impacts of moderation strategies for public displays will help to build trust between different stakeholders such as display owners and users. In addition, it will cause public display content to become more dynamic and therefore more interesting for the users.