Buttons and texts on my android mobile device appears smaller than what is in the game scene

I am new to android development and I didnt know what is the best engine used for making android games but I choosed unity and I found that implementing the game loop is easy but my problem was in making buttons and texts … they appear smaller on the device and for example if my mobile’s screen is 480*800 if I put a text at (240,400) It will not appear at the center so I cant handle this .
1- Is there a better game engine to be used while making android games ?
2- How to handle my problem in unity ?

Are you using UGUI for Unity 5? If so, you just set the anchor to center instead of top left. Then it will stay center regardless of resolution.