Open PhpStorm, click File, then click Setting
then
Click Apply, and you can see the effect of the change theme, followed to set the font, first select a style, and then click Save As, and name, I chose the last one, named WarmNeon_1 -------- after --------- save, setting font sizes available! ! !
Then you saved is to choose the style, which is you can set the font size
Finally Apply enough