i understand that there are already guides about this beforehand. And what i am sharing is not a groundbreaking technique, just a simple way (for me) to do the process, and it only takes seconds to do it.

Big question: Does Gallery Preview matter?
For me, it's a bit of both: yes and no.

I used to not care much about it, but after visiting the gallery of a user I admire, and then looking at my own, I finally understood the importance—lol.

Your gallery preview is like a book cover. It's the first thing people see when they visit your profile gallery. Sure, they might be wowed by your amazing profile, but most people usually check out the gallery next if they’re curious.

Of course, the original image quality is crucial, but a great preview can definitely draw more clicks.

So, YES, it matters if you care about your shots and want others (especially new visitors) to enjoy them as much as you do. But, NO, it won’t make a difference if the shot lacks effort or quality.

But if you’re reading this guide, I’m guessing you care, right?

Before we dive in, a quick note:
It seems that your preview image's file size counts toward your Steam Cloud storage space (you should have a total of 19GB). This storage doesn't just include your gallery—it also holds other things like save data and other game-related files.

So how do we change the preview? answer is simple:

• go to your steam screenshot manager, right click your recent shot of the same game, and pick "Show on Disk"
  
• Next your file explorer should pop up with the corresponding folder, what you need to concern is the respective image and the folder thumbnails
  
• if for example your image name is [20250124061614_1].jpg, then there is a copy of the same image file in the thumbnail folder with a much lower resolution, i think around 200px max width/height. And this very low res image is what steam is using for the gallery thumbnail.
  
• so the solution is to resize your image file and put it in the thumbnails folder with the same name
  
• There are many ways to do this, you can use photoshop, Gimp, acdsee, whatever image editor that you like and do this
  
  My Personal Favorite way is using Image resizer:
  install it from here (it should be safe since Microsoft themselves release this tool)
  https://learn.microsoft.com/en-us/windows/powertoys/image-resizer
  the page contains animated gif of how to use the tools, so you should understand where this is going.
  
  so my process is:
  
• Select the image/multiple images that you want to upload, Right click drag them to thumbnails folder and pick "copy here" -- pick "replace files in destination"
  
• Now open the thumbnails folder, sort by size (your shot should be separated on top) or by date if you recently edit it
  
• Select your image/ images, right click and pick Resize with Image Resizer
  (You can shorten this process by Right Click dragging the image and pick resize from windows explorer, but since i am using custom file explorer, this process is unavailable for me)
  
  
• now this next step, you can test out what works for you, image clarity correlates with image size (and it affects file size) i read some people like 800px, some other more and some less.. Personally i pick 400pixels as the max value, so i can keep the file size small but having enough clarity in the gallery. Feel Free to experiment!
  
  Heres my setting:
  
  
  
• whats important is the max size, the 'Fit' aspect ratio, and for me the 'Overwrite files' so i don't have to rename the files all over again

this is how my gallery look before

this is how it looks after




That's it !!
If you have some more tips, feel free to share it below, and if you experimented with the setting and find a value that you like better, also feel free to share in the comment below.
i try to make these guides simple and concise,
so if you have constructive feedback, or if you spot mistakes, please let me know.
Thank you!! Sharing is Caring 🤍