wrong poster art

I am having problems with poster art Plex matches the movie but puts up the incorrect poster. I am also following the correct naming conventions for movies. I don’t see this problem with all movies just certain ones. So how should I approach this problem?

Which naming convention are you actually following?
Only this one is the ‘right’ one: https://support.plex.tv/hc/en-us/articles/200381023-Naming-Movie-files

Do the following:
Go to Settings - Server - Agents - Shows - TheTVDB
In there, grab the line ‘Local Media Assets’ with your mouse and drag it downwards, so it ends up being at the bottom of the stack of active agents.
Repeat the same under
Settings - Server - Agents - Shows - TheMovieDatabase
+
Settings - Server - Agents - Movies - Plex Movie
+
Settings - Server - Agents - Movies - TheMovieDatabase

After doing this and making sure that your files do indeed follow the right naming convention, perform the Plex Dance with the problematic movie(s).

I am doing
Movies
Inception (2010)
Inception (2010).mkv

Let me follow your suggestion

@mstephens1754 said:
I am doing

Movies /
  Inception (2010) /
     Inception (2010).mkv

Perfect!