Uploading images into gallery with memory limit error

I’ve been using FIA Gallery plugin to showcase my designs, illustrations, photos, and other type of images and was able to successfully upload most of them using a gallery name for each subject except my ‘graphic design’ images (same size and similar KB’s as the others) but whenever it uploads an image relating to this particular gallery of ‘graphic design’ it comes up with a “error” message saying it ‘exceeded memory limit’ (64.75 MByte). But I have been able to upload a few images in that gallery but other images I can’t. What could I be doing wrong or not knowing? They are pretty similar.

How can I show my gallery pics with just individual frames with a description instead of a slideshow gallery? Haven’t figured that out. I’m using OverALL WordPress Theme 1.3 by Codestar.