So, I've been working with Music Creator 6 Touch lately, and it's giving me quite a few issues (I have many complains about UX design, but that's an issue for another day).
 
Anywho, so, for whatever reason, sometimes when placing notes, I guess I do something to change the velocity. The result is that I have a drum track where some notes are set to the velocity of 100, others at 105, 0, 125, 90, and so on. In my experience with other music creation tools, this is only a minor inconvenience. I want to simply select all the notes, and change the all notes selected to have the same velocity (in this case, I'd prefer 100). This is an ability that is also really useful when the UX is working as I'd like, but I decide that some notes should be louder.
 
But, I don't know how to do that. I can select an individual note and change its velocity. But I can't seem to do that for the group. This is causing me an enormous headache. Doing this manually, note by note, would add hours to music development to do something that shouldn't take more than a few seconds.
 
So, any help would be greatly appreciated. Thanks.

I don't have MC, but I assume MC has a function called Scale Velocities  like other CW apps. That one should do what you want.
You can  type either rising or descending figures in the box, or write the same in both boxes of the Scale Velocities-pop-up.

Searching for Scale Velocities helped. It was buried under a long series dropdown menus, which begs the question how this is considered to be designed with touch devices in mind. In any case, that allows me to set the values much more easily (read: possibly). Many thanks.

MC6touch is the very first touch capable DAW.....  Give them some time to figure out the design bugs in a touch based system. But on their side of this, they have a ton of features and functions to cram into very limited screen real-estate.... something has to be hidden down a few levels...and I think they probably placed the most used function up top and the lesser used items further down.
 
Which method were you using to edit the velocities?  Staff view or PRV? 

I had been using the PRV (although I tried editing the velocities in both). I want to use the staff view, since that's how I'm most comfortable writing music, but I'm not familiar enough with the intricacies of how the staff editor works to write music efficiently. Hopefully I'll get into it more later though.
 
In any case, my primary issues with the touch controls is that some features are accessed by right clicking, and others by clicking and holding. Which is weird, since right clicking is clicking and holding in most touch devices. Works fine on my tablet, but when I move to my desktop, it makes things a little cumbersome. It's tweaking little things like that example that turns UX design into something super intuitive.