Hi everyone,
I just started creating a game, i haven’t other 3d software despite blender 3d (which I think is quite difficult) and I am trying to enlarge a door wall but the door changes with it so i tried to fix it by using multiples walls. The problem came when I put the textures, which result is this:
How can I fix the textures?
Is there another way to create that wall?
Thank you! 
The problem you’re seeing is the indirect lighting caused by lightmass.
You can reduce this by going into world settings > Lightmass > and adjusting Indirect Lighting Quality (2 or higher) and Indirect Lighting Smoothness (~0.6). This can help.
For additional information take a look at this thread: Modular Asset Lighting Problem - Rendering - Epic Developer Community Forums
Also keep an eye out on this wiki tutorial for lighting troubleshooting and tips: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums
There are plans to add this there as well, but that’s at least another week or two out before Eric and I will have an opportunity to get it finalized and up for everyone.