When creating a new navigation display the option: "Allow overscale symbol" is always enabled for all objects and all selected computations:
When working with underwater objects with linked items (Trenchers, Fall Pipe ROV's, ROV's, ect) you will get a lot of overscale symbols when zooming out, which can clutter you display. You need to disable this option manually for each object and each selected computation.
Add an option to disable the overscale symbols for all objects and computations at once
This might result in objects, including the main vessel, to disappear from your Navigation Display when zooming out. Please remember to always enable the overscale symbol for your main vessel. See also the related issues FQI-521 and FQI-524