How do I make a Word resume that applicant tracking systems can read easily?

Build it simply, with Word's own structure tools rather than visual tricks. A checklist:

• Start from a blank document or a simple single-column template without text boxes or tables.
• Type your name and contact details in the main body at the top, not in the page header.
• Use built-in heading styles for section names such as "Work Experience" and "Education".
• Use Word's bullet list feature for achievements.
• Set a right-aligned tab stop for dates instead of pressing the space bar.
• Choose a common font such as Calibri, Arial or Cambria.
• Keep images, icons and charts out, or make sure nothing important is inside them.
• Remove comments, tracked changes and hidden text with Inspect Document.
• Save as .docx.

Then test it: save a copy as plain text and read it, and export a PDF to run the copy-and-paste test. If both show complete text in a sensible order, you have a Word resume that should handle most systems well, and you can also export it to PDF when an employer prefers that.