Image size when inserting into a branch

Dear Sir or Madam, when I insert images from the library into a branch, they automatically have the dimensions 14 x 14 mm. Sometimes I need a topic-specific image collection. To do this, I create a new folder in the image library and copy the topic-specific images from another, different folder into it. When I then insert these images into a branch, they have the dimensions 50.8 x 50.8 mm. How can I ensure that the images from the new folder also automatically have the dimensions 14 x 14 mm when inserted into a branch?