Select a frame, position your mouse cursor over it, press left mouse button.
In the top left corner of the selected frame, press zoom button -
the image will increase by 10%.
Press and hold left mouse button on zoom button
- the image will increase automatically.
Once you have increased your image, two more buttons appear next to zoom button.
The leftmost button
restores the original size of the image, while the button
next to it reduces image size within the frame.