First, remember ALWAYS (with VERY rare exceptions, not relevant here) to draw your geometry on Layer0, which should be permanently set as the Active Layer (its radio button checked in the Layers window).
Second, every time you have drawn a new piece of your model, make it into a component (or less usefully, a group).
To do that, triple click on any part of what you have just drawn to select all connected geometry, then press letter g on the keyboard, to start the Make Component dialogue. Give it a relevant name (such as Floor 1, Living room walls, etc).
Ensure the box Replace selection with component is checked.
Set the component axes if you don’t want the default bottom left corner.
Then click the Create button.
Once you have your geometry collected into components or groups, assign Layers to one or more of them. But NEVER to raw geometry.
Hope that helps.
PS. To reset all your existing geometry to Layer0, open each component, sub component, or group in turn for editing, Select All, then in Entity Info, assign Layer0.
THEN, to control visibility, assign layers ONLY to top level components or groups.