Changing word template for knitr in Rmarkdown

I prepared a video for this task. Please see if it helps. Basically you generate a Word document from an arbitrary R Markdown document, then modify the styles in the Word output document, and use this document as the template for future R Markdown documents.

To use a specific template or styled document, you can create a file with the appropriate styling and reference this file in the YAML header of your markdown file. As described in this article: https://rmarkdown.rstudio.com/articles_docx.html

---
output:
  word_document: 
    reference_docx: "filepath\\ref.docx"
---