EquatIO allows you to author equations, but you don't always have to start from scratch. If you'd like to work with an existing equation, the Screenshot Reader tool is a helpful option. How the Screenshot Reader tool is used will vary slightly, depending on which version of EquatIO you've installed.
Desktop
If you're using the EquatIO desktop client, select the Screenshot Reader in the EquatIO toolbar and draw a rectangle around the equation with your mouse.
Click the three-dot button and select Edit in EquatIO. Now you can make changes to the equation, if needed, and Insert Math into your working document.
If you need to make changes to an equation you've inserted in your working document, use the Screenshot Reader to capture the equation and edit within EquatIO. See the following video for an illustration.
Browser
If you're using the browser-based version of EquatIO, the Screenshot Reader can still be used to edit existing equations. Please see the guidance from EquatIO.