Just about every week someone will call and say "My Easyboot Gloves don't fit." I ask what the problem is and they say they are too big and won't stay on. So I ask a few questions including, "How do you put them on?" Their answer is something like "I just push them on with my hands."
"Oh there is the problem" I reply. "You should never be able to just push them on with your hand, they are either too big or not going on all the way. If you have the right size boot then you really need to bump them on with a rubber mallet to get them totally over the hoof and have them seat well for a great fit. I'll get over there to help you out with them and show you." Occasionally the boot is the wrong size, but most often, they just simply aren't going on the hoof. When I show them the mallet trick in person they say, "Wow it looks so different. It's hard to believe that's the same boot. I need one of those mallets. "
You can purchase a rubber mallet at your local hardware store for less than $5, a cheap tool. You'll find a lot of other uses for it too. I keep mine in my gear bag with my boots. When I first begin to apply the Glove I push the boot over the hoof as best I can with my hand. I give it a couple thumps with the mallet right at the toe to shove it back so it goes over the heel.
Once the boot is placed over the heel, I give it a couple good thumps above the heel area to drive it down and really get that heel into the boot. This truly seats the hoof down into the boot. You should be unable to move it any direction with your hands, it shouldn't twist, turn or come off easily. Then I lower the hoof to the ground. If the boot is straight and on the hoof correctly, I velcro the gaiter and I'm ready to go.
Properly applied boots with a good fit stay on through just about anything. So go ride and don't worry.