image sizes greyed out when inserting image

hey, i’m new to using the wordpress software away from wordpress.com. i notice the image controls are different. i’ve tried to insert an image into one of my pages, but the image size options (small, medium, large) are grayed out. why is this? is this related to the theme i’m using? or is this for another reason? i was able to resize it another way (by clicking on the little resize button once the image is inserted into the page), but i liked the small, medium, large options. site: http://manofarm

hope this makes sense…