While logged into your website in admin mode, simply click on the photo to change the image style.
In the menu to the left, under "Image Filter", click the drop-down menu.
Select filter that you would like. To choose a pointed-corner style, choose "No Filter".
Continue to apply the same filter to change the look of each photo through your website.
Tip: The best style is to set the same Image Filter for every photo on your website. However, at least, ensure that photos on the same page or sub-page have the same "Image Filter".
Encouraging tip: Once you do the first image, it will not take long to systematically make the changes throughout your site.