When we import .docx files into QuarkXPress project with endnotes which have different formatting. Each endnote is a separate story in QuarkXPress. Therefore, it is not possible to do Command A or Control A to select all the endnotes together.To format the endnotes please follow the steps below:

On importing the word file, a new MS Word endnote style gets created and applied automatically on the endnote references

Create a new paragraph stylesheet with desired formatting

Invoke Footnote styles palette

Edit the MS Word endnote style

Modify the paragraph style in the footnote/endnote formatting section to the new paragraph style sheet
The formatting will get applied to all the endnotes having the same MS Word endnote style.