Alvindra - you can manually set the pixel size for each column with the following line of code
set(handles.uitable1,'ColumnWidth',{50, 100, 150});
where the pixel widths of the first three columns 50, 100, and 150 respectively. In order to determine the pixel width of each column, you would need to determine the longest string in each column (in pixels). To determine the size, see Walter's answer at http://www.mathworks.com/matlabcentral/answers/56317-determine-size-of-text-objects.
