Some featured images won't resize in TG: services widget

Although the Spacious theme scaling feature does change the image size in terms of it’s properties, the images often still appear full size in their appearance in the widget. Is this a CSS issue? As I am making a mock up of my site and using images from the web, might this be part of the issue also? Generally speaking, is it best practice to achieve desired image sizes in image editing software prior to uploading?
Thanks in advance.