whatr do you name your tv series files?

The reason i ask this. Most of the time i have no problems with it finding the correct meta for each series. but ive noticed something and now ive noticed it, it has become a bit of a issue.

So i have my son on my plex account so i know what he is watching and not filled with adverts every 5 seconds.

What i have noticed is on his power rangers series. the meta and all of the episode info is displayed.
So the main picture on plex is the standard power rangers picture with a discription.

you click on this and it takes you to the next screen, where each individual seasons is in there. they all have their own pictures apart from season 6. This season shows the same picture as the original screen picture. (If that makes sense )

The when you click on season 6 it just says : episode 1 ( then 2, then 3 you get the idea) next to each screen shot of the episode.

now ive gone in to the original drive and renamed all the episodes like the other series but it will not change this at all.

Ive also noticed season 17 shows the correct picture for the season but when you click on it, it then shows the episode 1 and so on. istead of the title for that show.

Hope this makes sense but can anyone help me please

first thing to do would be checking the naming adheres to the standards outlined here https://support.plex.tv/hc/en-us/sections/200059498-Naming-and-Organizing-TV-Shows and also checking the information for that TV Show on http://thetvdb.com/