I've only found a few videos for customizing drums on Tyros4 and all are very old, means bad quality (blurry, camera shaking, etc). On of them is made by member of this forum:
https://www.youtube.com/watch?v=sbcjZ5p7R30-turn captions on and "auto-translate" to english
I can't say how useful that video is, because I don't own this keyboard and so for me, it looks quite confusing.
To understand how editing/customizing drums works, I recommend the following video. It explains very well (slow and step by step):
https://www.youtube.com/watch?v=aEsAjB-73nE-you might also turn on captions, though.
The second video link (above) shows how to do it on
PSR-SX900, which is in my opinion, much easier & logical than on Tyros (but as said, I don have Tyros). Regardless, once you figure out what buttons you need to press to get into right options window, the process is basically the same on both keyboards. I recommend that video, just so you will know what you need to look after (on Tyros). As you can see on that video, on PSR-SX (and on Genos) it all starts with "Drum setup" option (once you're inside Style editor) -on Tyros, "Drum setup" is obviously called different.
A short explanation for those who are interested, but never really tried:
In every real band, it's the drummer who is responsible for rhythm. In keyboard case, style is the band and Drum-Kit is drummer's equipment -a drummer obviously uses more than one instrument. Now, besides the rhythm, he also needs to make sure, that (for example) loudness of each instrument (drum, snare, etc.) fits into music that band is performing. But there is no drummer in our keyboard, so it's up to keyboard player to adjust drum-kit properly in forward, so the drums fit the music we're playing.
We can open drum-kit as a voice and if we do that, we can hear various drumming instruments depending on which key we press. And the more we hit certain drum instrument, the louder it will be. But when the style is running, we can't influence the loudness of each drum-instrument anymore -we can only change loudness whole drum-kit. In short: built-in drum-kits are generic (not adjusted for any particular music or song). Built-in drum-kit should only serve as a basis, from which we can start customizing drums sounding, so it will sound properly for that particular music -by assuming we wish a "perfect" result.
And that's what "Drum setup" is for. Here, we can adjust many parameters (loudness, reverb, etc.) for each and every key (=drum instrument) on keybed. For example, we need tambourine to be louder? Or only main drum quieter? We find the key that plays tambourine (keyboard DataList can be of big help here) and adjust the loudness of that particular key -it's like we would adjust key touch sensitivity for each key separately.
Now, that loudness (of that particular drum instrument) will be valid for whole style. To change loudness inside pattern (for example: 1st hit louder, 2nd one quieter, etc.), then we need to use "StepEdit" to accomplish that.
That's it.. I hope I wasn't too boring and that I raised the curiosity for some.
Bogdan