previous demos and the PS4 UI Modding Database, today PlayStation 4 Modder @Thisismrnameles shared a PS4 Custom UI video demonstration HERE showcasing changes in the system app icons for PS4 Firmware 1.76 consoles.
Below is a brief guide from the demo video by Hydrogen, as follows: How to Mod Your Own UI Application with FTP 1.76 PS4
1.) Turn on your PS4 Console.
2.) Connect your PS4 to a FTP Server (FileZilla).
3.) On FileZilla, go through your directories from the following and find the game/app you want to change: User > appmeta
4.) Drag the game folder or application folder into a brand new folder. Open it there, and you should see all the meta data for it. From here, "icon0" is the image of the application.
Quick Note: The images have to be 512x512 size, or this will not work. Also, 1st icon0 is a .png, and the 2nd icon0 is a .dds. Pic1/pic2/pic3/etc are always 1920x1080.
5.) Now get your image you want, and make sure you re-edit them to a .png file, and a .dds file. Afterwards, drag and drop them in.
6.) Drop the folder you were editing back into your game applications from FileZilla on your PS4.
7.) Restart your PS4, congratulations you have now created a UI Mod on your applications.
Thanks to @raedoob in the PSXHAX Shoutbox for the tip and @HydrogenNGU on Twitter!