If you customize background and icons of apps on the Deck from your Steam win client, the changes are not propagated.

[Numenorean]

I added custom games on my Deck, and as expected they look bad since there is no artwork associated with them. When I turn on the deck I can see those Deck games showing up in my library on my win Steam client, as stream.

So I tried to modify those, adding custom background and logo; which did work fine. Although once I turn off the deck and turn it on again, the changes are gone from Steam Win client and they never even show on the Deck.

This look like a bug to me... Either the changes should propagate to the Deck; or the option to customize something that is on a deck should be disabled. Otherwise it make no sense adding customized background and logo for games you add manually, when these changes never sync to the Deck nor even stick on the win steam client

[monkeyfritz]

Customize them from desktop mode on the deck itself. Whats happening is your win steam is just making a temp shortcut for streaming. the same thing would happen in reverse . ie: You had non steam shortcuts on the win machine, from the deck they will be blank. No custom images are added to your account, they are only stored locally, never shared between machines.

[my new friend]

They have only ever been locally stored per device, even on PC. This is why https://www.steamgriddb.com/ exists.

[Zombie]

Both answers above are what you want, first grab the grid image, and an icon for the game you want, then reboot to desktop mode, open steam, in the library view then "right click" using the left touch pad and scroll to manage > add custom artwork, here you link the grid image. Then after click on the non-steam game and click manage (gear icon), then properties, up above click the square, it will let you add a custom icon. After that's done close and reboot to game mode, and it will stay. The only thing that looks ugly is the horizontal image in recently played etc, I have no clue if we can ever fix those, not even desktop lets you mess with those as far as I am aware.

[monkeyfritz]

@Zombie

There is a way to fix that, but it's stupidly unintuitive.

In desktop mode, in library view, the recently played list shows only the most recently played game with the horizontal image. Then you can right click, and set custom image the same way as before.

You can go out of your way to download a second image that looks better, or just reuse the same poster image.

This works, but it means you have to launch each individual game, close it, then change the image while it's the most recently played game.

They really really need to add a settings panel to let you change all the custom images at once, and preferably have it in gamemode too.

[mannamation]

I tried all your suggestions with no luck? I cannot right click at all

[nicoper]

I use syncthing[syncthing.net] to sync custom artwork between my desktop PC and my Steam Deck. Works great!
The folder you want to sync is <steam-install-dir>\userdata\<account-id>\config\grid