When do i need to pay attention?

The moment you get to see Gweneth again after the betrayal and need to choose her fate.

Each of the 3 choice you make with her will be an ending.

Follow the following steps before you choose.

1. Save the game before you talk to Gweneth.
2. Quit the game.
3. Press Windows+R to search.
4. Type in %localappdata%
5. Locate Winter Ember and go to savefiles.
6. Be sure you got your correct save file. (should have a -1 behind it)
7. Right click it and go to properties.
8. Set it to Read Only and Apply.
9. Start the game back up, load your game and make a choice.
10. Kill the boss and an ending will show up.

All you have to do now is quit to the main menu and load back up again.
It will set you at the choice again instead of saying you finished the game.
All you gotta do is choose a different choice and finish the boss again.

Repeat for the 3th achievement and done!

Hopefully i've helped some of ya with this ^^