Welcome.

Before the course is published the textual content is contained within {installlocation}\adapt_authoring\temp\{yourID}\adapt_framework\courses\{yourid}\{course number}\build\course\en.

Once you have downloaded your course to a zip file you can edit the content in the json files contained in coursefolder/course/en - but bear in mind that the changes won't then reflect back into the course itself back in the authoring tool.

Does that help?