Rolling over

[Mez80]

I don't know what to do about this but i break out in a sweat when i change DDs nappy and or clothes...
She just wants to roll over and crawl away. She doesnt wait for me to take her pants off/unclip her body suit or to take her nappy off. She just goes. It makes the task very difficult.
I have tried a firm no and she looks at me and off she goes. I have tried using that safety strap that comes with the change table but she can still turn around from under it b'coz of course its not tight.. i have tried singing, making silly noises, talking, giving her toys.. sometimes i change her on a mat on the floor and i have to sit her in my lap to dress her once her nappy is on.
I know this is probably unusual and that i have tried lots of different things but am hoping for some suggestions.