See levels when working in a 3D view, and adjust level heads in the view as needed.
This video demonstrates the following:
When working in 3D views, display levels to help you understand the position of elements in your model. Levels can be displayed in both orthographic and perspective views.
In a perspective view, levels are not displayed by default. Turn on the visibility of the level category to display the levels. Levels displayed in a perspective view never show level heads and are always drawn with a solid line.
Levels are visible by default when you create an orthographic 3D view. Working with models created in a version prior to Revit LT 2019, you will need to turn on the level category in the view.
When a section box is not applied to the view and you select a level, the resulting plane highlights to represent the 3D extents of the level. Use the open control grip to adjust the 3D extents of the level. Use caution when adjusting levels in this way as it can affect the level indicators in other views.
To affect the level indicators in only the 3D view, first apply a section box to the view. On the Properties palette, select Section Box and use the shape handles. The level indicators will adjust with the section box position. Right-click and hide the section box.
As you navigate the model, the level indicators will reposition themselves to always remain behind the model. Turn on a level head indicator with the check mark near the end of the level line. Click and drag the blue dot control to reposition the level head. Level heads cannot have a shoulder in a 3D view like they can in sections and elevations.
Use levels in 3D views to help understand and present your models.