Available editing options vary slightly depending on what type of shape you are working with.
For instance, as explained below, the resizing band of your zebra tool will alter arrows and lines differently than it does other types of shapes.
Clicking, holding, and moving your mouse in the shaded area of the zebra tool will widen or narrow a selected arrow or line, but will not change its length. You can also accomplish this by clicking the "+" and "-" buttons in the same area of the tool.
Performing this same action with other types of shapes will not work in precisely the same way. You can alter the length, but not the width, of drawn elements. Highlights and the perimeters of geometric shapes and frames will rescale proportionately. In other words, highlights will become either wider and longer or narrow and shorter, while perimeters will will widen or narrow slightly as geometrical shapes and frames are resized.
Note also that by default, selecting and resizing a frame or geometric shape that surrounds text or images within its boundaries will also alter those items it contains. This can be advantageous, ensuring you resize all these related items to the same degree. However, if you wish to edit a frame or geometric shape alone, simply hold down the "alt" key on your keyboard ("option" on a mac) when you click it with your mouse. To alert you to this decision, the zebra tool will display as yellow rather than blue; note the distinction below.
Double-clicking a frame, arrow, line, or geometric shape will render visible its "editing nodes." In the case of frames, rectangles, and triangles, these nodes will allow you to alter the proportions of the selected element. Note that circles will simply be resized; one cannot make them ovular.
In the case of arrows and lines, the editing nodes permit you to change the length of a given element. For example, three circles appear on the arrow shown below.
By moving those on the end, one can change the length of the arrow. If one moves the central circle, one can transform the line into an arc. This is also true of lines; see the below video.
As for other elements, Prezi will aid you in scaling arrows or lines to the same size. If for instance you aim to make two arrows the same length, you will find that the arrow will pause slightly, or grow "sticky," when the proper length is reached. See the below video.Note that no similar option is available for geometric shapes, highlights, drawn lines, or frames.