strange icon for Pot player

That is the default icon.

If you want too change it to the old one try this in Preferences.

(Try PotIconsNew pack for square icons)

In addition you should configure:

Settings file is stored here:

"C:\Users\Username\AppData\Roaming\PotPlayerMini\PotPlayerMini.ini"

and here:

"C:\Users\Username\AppData\Roaming\Daum\PotPlayerMini.ini"

You should back those files up to another location. They can be restored to their original location if they ever get overwritten when installing an update.

By the way I've been using PotPlayer for probably a couple of years. If you don't already have it consider MadVR plugin.

madVR

About: MadVR - madVR configuration and optimization guide, screenshot comparisons and algorithm performance

Basics:

Setup takes a little work. You'll need to download madVR and unzip it somewhere safe (you can't delete the folder later); run Install.bat as an administrator; run madHcCtrl.exe to access your settings.

I use this but leave the other MadVr settings set to defaults:

Then choose madVR as the video renderer in your media player (in PotPlayer, Video > Video Renderer > Madshi Video Renderer).

But once that's out of the way, madVR will be used for all playback, and you can start trying out its various processing, scaling and rendering options.

In addition for thumbnail previews on timeline in PotPlayer:

You get used to the icons. As far as I can work out icons were changed in version:

[1.5.40688] 2013/10/17

PotPlayer Version History - VideoHelp

It's probably best to keep using the current version but if you really wanted old icons you'd have to install an old version and disable update checks:

Old versions are here:

Potplayer for PC Windows - History - FileHippo.com