Making changes to a purchased embroidery design is done with editing software.  Machine manufacturers include editing functions in their own embroidery software packages, but you may be able to use other embroidery software if it handles your embroidery machine's format. Some embroidery machines now come with editing features built in, but editing software has more options and can handle larger files.

Editing features that are useful in an embroidery software package include:

Options for re-coloring sections of designs, including blended thread options for cross stitch software.

The ability to combine multiple designs to create a new design.

Rotating and mirroring functions.

Tools to remove unwanted areas of stitching.

A way to increase or decrease a design’s size.

Design splitting features help you to divide a design that is too big for you machine’s hoops into smaller parts so your machine can stitch it out.

Alignment features help to invisibly join design parts for multiple hoopings after they have been split.
They are also helpful when repeating a design in order to create a continuous border.

Stitch re-ordering options to help a design stitch out better if you've changed the number of colors or
added to or removed parts of it.

Text tools for personalizing designs. These are also known as keyboard lettering because the letters are typed into the design.  Text tools generally fall into two types – font packs, which are groups of alphabets in limited styles and text generators, which create lettering from the fonts on your computer. Some software allows you to apply different styles or patterns to the lettering, while other software allows you to create monograms.  

Pattern libraries make it easy to add additional details to your embroidery design. Some software also allows you to change the stitch patterns in a design to others included in a library.  

Some useful editing functions are specific to the software’s embroidery type:

In cross stitch software, the ability to import existing charts is a useful feature.

In machine embroidery software, a density change feature allows you to change the amount of thread coverage in a design, which helps designs stitch well on fabrics of different weights. Format conversion capabilities can change a design into multiple machine embroidery formats, which allow you to use designs that are not available in your machine's format.