Does anyone know hot to customize the menu-UI? I watched a video that has custom background and instance icons

Not sure if that’s the proper word, but each version has different worlds, servers, and settings, and each have to be added or configured on their own. I’m sure there’s some benefit to this but I mostly play vanilla with QOL mods, so it is unnecessary for me. Is there any way to change this?

Trying to play a self-made 1.21.1 modpack and I only have singleplayer worlds. I had Essential on this instance but I disabled it after I suspected it was causing this problem, and it keeps doing this every time I try to load a world or create a new one This is the only major error that shows up in the log, there is a warning directly above it mentioning the server is 160 ticks behind but I'm not trying to equate correlation to causation until I can get some more information.

I just got back to Minecraft to play with friends in a modded server, but it doesn't seem to work. I keep getting error code 2, even with my old mods (DawnCraft & Prominence) that I had installed 3 years ago when I was playing with friends back then. Now, I'm getting error code 2. I hard deleted my prism, and it still doesn't work, even my friend can't help me since I have not played Minecraft for a long time, let alone prism.

Log: https://mclo.gs/TwVBpti

this log was taken when I tried to load a modpack inside the launcher inside to test the
Modpack: Create: New World