Is it possible to make images bigger?

Yes you can use a stylesheet to override the settings…..

Change #wptime-plugin-preloader

for me it was set like this and the image was really small even though my image is actually 200×200

-moz-background-size: 64px 64px;
    -o-background-size: 64px 64px;
    -webkit-background-size: 64px 64px;
    background-size: 64px 64px;

To the desired size you want…. but like he said 128px to keep it retina ready.

So in a separate style sheet you add in the “!important” to override the plugin settings…