It may be possible in some aircraft, but I promise you that the problems you're experienceing are procedural. I fly aerobatics in real life, and I can outline how some various rolls are performed. Of course, it's only a sim and you can fly things however you like or want to see, but if my advice helps you then you're welcome to it.
Slow rolls: start level and at a fairly fast speed. pitch up five to ten degrees, and start a constant and slow rate of roll that you will adhere to for the entire maneuver. Use the following controls in a increasing then decreasing manner to keep the nose relatively in the same place; rudder, nose down pitch, opposite rudder, then a small amount of nose up. While inverted your nose should pass slowly through the horizon on it's way to the opposite of the value you pitched up too. When finished you should be at the same altitude you started at bt pitching up for the horizon. Your altitude change should be minimal throughout the maneuver.
hesitation rolls: use the same principal as a slow roll, but go max aileron with small opposite inputs to make it punctuated when you hesitate. While hesitating, keep the nose up with rudders or pitch. Add four, eight, or as many points as you'd like.
barrel rolls: Use a moderate amount of aileron, rudder and pitch to go up and around. You should gain and lose a fair amount of altitude, with your nose passing through the horizon at the exact point you're passing through wings level inverted flight. When you finish, you should be at the same altitude you started at. The maneuver should look just like you drove all the way around around the inside of a tunnel. Note that this isn't a rapid maneuver.
Loaded rolls: this is similar to a barrel role in flight path, but you're building a big AOA and keeping it, therefore making the pitch you use more than the roll. This maneuver should be exclusively for modern high powered aircraft, as it's done slowly with high power settings to overcome drag. This is probably the one you saw, but you're not doing it right if you go flat out with the pitch.
aileron rolls: pitch up slightly, use max roll and a medium amount of rudder. To make it snap, apply slight opposite aileron at the end to bring it to a stop.
snap rolls: at a slow to medium speed, suddenly apply full nose up elevator and full rudder in the direction you want to snap. don't use aileron to help, but if you need it to stabilize at the end, then use it. You're literally making the aircraft attempt to spin, but you're maintaining positive control. You shouldn't be able to accomplish this in jet aircraft, nor should you try in real life, but once again, it's a game. Try if you want, but it's not a true snap roll in a jet.