Mbot3d Cube: Oversized Prints


i have the above listed 3d printer and it all seems to be working OK the only exception being prints seem to be coming out to large, the most noticeable and prime example being when printing iPhone cases.

I Have tried the gcode generated from stl’s created from services like thingiverse and zetoff both seem to yield the same results. These being the case being to large around (8-12%). A couple of calibration cubes have also printed larger than they should. leading me to believe its more settings than model issue.

Can anyone shed alight on what setting is wrong, or what im doing wrong.

Many thanks