The first thing to do is to get away from computers and your piano. Ear training is in the head, you need to train your brain, your inner ear, the piano is a crutch that will slow down your training. First, be able to sing a scale (away from the piano) but instead of singing, letters or syllables, sing numbers: 12345678. Now make sure you can pick out the 1, 3, 5, and 8. Again, away from the piano, you are training your brain, it doesn't matter what key you are in. Letters are absolute, numbers can be anything.
Ignore silly tricks like STAR WARS is a fifth. In the heat of the moment you don't have time to think of a song interval. You just have to do it. You need to know what the fifth is without thought. Just listen to the bass or tuba play in any polka band. The root's best friend is the fifth.
Now go lay down on the sofa with a piece of paper and transcribe the song MARY HAD A LITTLE LAMB. I'll give you a hint, it starts on the third. Now figure out the numbers and write them down. If you want to check your work, you can play them on the piano later. Again, it doesn't matter what key because we are dealing with numbers, not letters. Start on the third of any key and sing the numbers. It is also vital that YOU SING. That helps to hardwire the intervals into your brain where true muscle memory resides. Singing numbers is also the secret to sight transposing. These are the numbers I plucked out of the air:
3212333 222 355 3212333322321.
Let's try another, ODE TO JOY. It too starts on the third. What a coincidence. Once you transcribe a lot of songs you'll discover that they have everything in common:
Here is an easy one, JOY TO THE WORLD. It starts on the 8:
8765 4321 56 67 78.
Notice the 1, 3 and 5 are common target intervals.
If you wrote out these songs without cheating, no matter how difficult, you are well on your way to being able to improving your sight reading, transposition, improvisation and just knowing the notes to any song you hear.
Go to your local Protestant church and borrow a hymnbook. Then go back to your sofa and sight sing the melody. Then try out the AT and B parts (SATB), always singing numbers. The beauty of working with a hymnbook is that all the parts are easy and harmonically repetitive and predictable. Often hymns are AABA in form so you get three chances at it.
Go to church on Sunday and on the hymns practice sight singing all four parts to the hymns. If there is a good choir you'll know that you are correct. If the organist plays the actual notes in the book, you'll know that you are correct. The church must have a good old fashioned hymnbook so try Episcopal, Methodist or Presbyterian. Don't waste your time in Roman Catholic or contemporary churches. They tend to sing songs and pass out lead sheets. Leave it to the church to dumb down music.
Again, ear training must be done away from the piano, software or books. Whenever you hear music, listen for the root and fifth then try to figure out the intervals. You can do this watching TV, commercials, listening to the radio, in malls, driving your car, laying in bed or lounging by the pool.
It may be difficult at first but will get easier with time. In a few years you'll be listening to Oscar Peterson and know every note he played.
Also, never EVER hunt and peck. If you are at the piano and you don't know the next note, don't guess. Don't train your brain to make mistakes. You only get once chance at muscle memory. Errors can be forever. Your brain doesn't get a reboot.