This is a common problem across many drawings, it can create confusion when giving drawings to customers as its showing lines from internal components that shouldn't be visible. Funny thing is if you zoom in on the drawing they disappear, but when printing or saving as a PDF they remain. Is this a setting or a bug? Would be great if there is a solution. This only occurs on shaded views.
Sheet Metal right? - this seems to rear up everytime I have to do a sheet metal drawing.
I have found sometimes it's not so bad. maybe related to thickness of SM??
I have tried turning up Image quality settings - not much change......
Maybe try options on this page.
Also anti aliasing under System /Display.
None of above does much apart from slowing down computer.
My best guess is a limitation in graphics rendering engine or card.
Other than that sorry not much help