Help Needed with Text Column Formatting in 20-Page Project (Primary Text Option ON)

To recap...

If you want the entire page in 3-4 columns, it's best to use different master pages or just override the default column setting. (Twenty page is not very long, so if it's only a few pages, I would just do an override as the easist option.)

If you want to do a mix of columns in the text, use the span/split Columns feature (with paragraph styles!). Keep in mind that the column settings will flow from page-to-page if the text reflows.

If you want a mix but need to keep the column layout static (on the same page), use two separate text frames and link them together. (For example, 1 column on the top half and 3 columns on the bottom half.)

I have the "primary text" turned ON

Hi @K-Ten , To leverage the power of Primary Text Frames, you would want to make a Parent spread setup as 2-columns. In that case you can easily apply different masters to the primary running text—more on primary text frame usage in this thread:

https://community.adobe.com/t5/indesign-discussions/can-someone-help-demystify-how-primary-text-frames-actually-work/td-p/8930818#9329177

Here the A-parent is setup as 1 column with Primary Text Frames (icon has an arrow)

A B-parent with 2-column Primary Text Frames:

Now if I drag the B-parent page on to page linked to the A-parent, the running primary text is updated to 2-columns:

I often make 3 or 4 Parent Pages: 1, 2, 3, and 4 columns. Then I apply them to pages according to my layout needs.

Also, you might rarely use the Primary Text Frame since you need to change type layout in some pages. I find it easier to make text frames as I need them.