Some title card issues...

Well, here's my problem. I was trying to modify the intro screen of Sonic 1 so instead of saying Sonic Team Presents it would say Paint Team Presents. I followed ESE's Sonic 1 hacking guide and did everything like it said. I played the ROM to test it and it came out all glitchy. Does anyone know what the problem is. This is my first time using hex and I'm new to this kind of stuff. Thanks.