I understand that you want to change the alignment of the labels to horizontal and position the title in the centre of the graph. To make the labels horizontal, you can use the xtickangle function. For aligning the title in the centre horizontally, you can refer the following code:
f = gcf;
% get the current axes handle
ax=gca;
% change the label alignment to horizontal
xtickangle(ax,0);
% set the title and align it in the center
title(ax,'Your Title', 'HorizontalAlignment', 'center');
exportgraphics(f, 'VC_Effect.png', 'ContentType', 'image');
Please refer to the documentation for more information:
- xtickangle function:Rotate x-axis tick labels - MATLAB xtickangle - MathWorks India
- Add title: Add title - MATLAB title - MathWorks India
Hope this addresses your question!