If you are afraid that your idea will be stolen once you present it to others, consider the following: Your idea is most likely not as revolutionary as you think. There may already be a similar or related app that solves the problem you're trying to solve.
At appleute, we encounter a "new" idea every day - the majority of ideas have already been implemented in this way or something similar. Often, intellectual property owners are afraid to test the existing existence because it is demotivating. This is treacherous.
Advisors and funders you may seek out to raise money to develop your idea - for example, to pay developers - are much less interested in exploiting your idea than you think. Rather, investors invest in your profile, i.e., your experience and expertise in the app-related field. When it comes to app ideas, experts share the view that investors care more about the "how" than the "what."