since you are new here, some generic advice:
1) it takes time, even when your learn things the correct way, it might take a week (or more) till you get good at something
2) in the Games section there are these Exercises where you can practice really fast, if stuck try to do these as well.
3) you can hit the pause button⏸ right after you give an answer and then click on the other options, how they sound, to focus on the difference.
4) practicinng in real-life on real instrument helps too. spend some time with the music ;)

Go slowly when you are doing the test. Sometimes when you hear a chord it might be coloured by the chord you heard before. Give your ears and mind some time to clear out the previous sounds. I hope this helps.

Everyone hears things a bit differently but for me it helped a lot to stop trying so hard. When I focus too much, the Major and minor flip in my brain because the Major is supposed to sound better or something? Idk, it's a mental trick I play on myself that maybe you play on yourself too.

The Major sounds... boringly triumphant? Try to paint your own, unmistakable mental image for the things you hear. I do a mnemonic of a gladiator in the arena having just won a fight - but it's a super cheesy 80s movie version where everybody is kinda just phoning their acting in. If I can't imagine that gladiators half-hearted whatever face, holding up a boring, triumph fist, it's not major.

A simpler one is the Major 3rd - it's a doorbell. If it doesn't sound exactly like a doorbell ring, it's not a Major 3rd.

I hope that helps you as much as it did me, good luck!!