problem with button touch zone

Hi everyone, I am making a main menu for my game in unity 5 but i came across a weird problem with my buttons. They work well, the script is fine but on mobile you have to touch them like one centimeter above the actual button to get them to do what they have to do. What strange is that they work perfectly on the computer. I have searched for a long time on the internet for a solution or an answer but none of them seemed to work for me.