If u see it tilted towards the bottom, try to look at it from bottom to up, and if u see it bottom to up try to see from the top to bottom (idk if that makes sense but thats how i find i can see them, tho ur brain quickly adjusts to the “default” whichever u saw at first), also blink..
Perceived one way, the side of the cube facing you is facing downward and towards your left and you are seeing the inside of the bottom face through the rest of the cube. With a shift in perception, you can see it so that the face towards you is angled up and to the right and you see the bottom face from below the cube.
Like this:
Now the trick is to make your brain do it without removing any of the lines.