Wall, ceiling and floor.

Hello,

I already made a topic about this a few days ago, but I don’t know how to close it, and I have a few new questions with it.

When playing Gmod I have a problem when it comes too making good walls, ceilings and floors. In some maps I download I see perfect walls, which cannot be moved.
But when I make them they are persistent for a while, but when I reload the map, they can once again be moved. A.k.a. they are not persistant anymore. This is very annoying because it is ruining most of my creations.

Should I use another way (tool?) to make sturdy walls, windows, floors and ceilings? Or can I fix the persistant bug where it ‘wears off’? I have been searching for a few guides or solutions on YT or Google, but I can’t find it there. So I hope anyone here can help me. If you need more information about my addons or OS, feel free to ask.