Trim the tape as small as you need to. I run calls with no tape at all. Just keep trying. It may not stay on the roof of your mouth without tongue pressure. No big deal. Just move it between you cheek and teeth to talk. I am sure you know this but, make sure the open end of the call is facing out. Huff air over the reeds like you are cleaning a pair of glasses. Use different tongue pressures and positions to get the sounds. Open and close your mouth with every note. That makes you move your bottom jaw. That alone will give you better sounds. Good luck.