ATTiny 841 programming using UNO

[STDummy]

Up until a month ago I was quite happily programming some ATTiny 841 controlled boards I made using the following parameters:

Unfortunately, my pc then died and when I installed the Arduino IDE onto my replacement computer (IDE 2.0.4), there doesn't seem to be an ATTiny841 (without optiboot) available.
The "ATtiny" or "ATtinyx41" boards don't work, I just get "no such file or directory" error messages.

None of the folder locations or names make any sense to me anymore! They've changed everything I thought I knew

Can someone please explain to me in words of as few syllables as possible - how on earth do I set the fuses for 8MHz internal clock and set the board as ATtiny841 so I can upload sketches to my boards now?

[westfw]

The tiny841 is part of the Dr Azzy's ATtinyCore.
I don't think ATtinyCore supports version 2 of the Arduino IDE (or vis versa.) Support for Arduino IDE 2 · Issue #742 · SpenceKonde/ATTinyCore · GitHub

[STDummy]

Ah, thanks for that @westfw . That would explain a lot. Right, I'm going to uninstall version 2 and download version 1.8.19 again.
The annoying thing is having to download all the cores again, seeing as I lost them all in my pc crash

[STDummy]

Hmmmm, thought I had it sussed, now I'm not so sure. I've installed the ATtinyCore, but even though adding http://drazzy.com/package_drazzy.com_index.json to the board manager, I don't see Arduino as ISP(ATTinyCore), only Arduino as ISP.
If I do upload a sketch that has pwm in use, i.e. led fading, on pins I know are (or used to be) pwm, I just get the leds constant on, no fading at all, i.e. -

const int led_A_Fade = 4;
int value1;
const int period = 1000;
unsigned long time = 0;         // stores the value of time() in each iteration of loop()

void setup() {
  pinMode(led_A_Fade, OUTPUT);
}

void loop() {
  time = millis();     // capture the latest value of time()
  value1 = 128 + 127 * sin(2 * PI / period * time);  // sine wave formula
  analogWrite(led_A_Fade, value1);
}

just results in the led being permanently lit.

Pin 4 is PA6

Tools set

EDIT:>>>
All solved now. It needed every trace of V2 of the Arduino IDE removed. I completely stripped out all Arduino files from the computer and started from scratch. Using IDE 1.8.19 and ATTinyCore ver 1.5.2 it all works as I want now.
Shiny new things aren't always better!!