I see many people have a similar problem, but I cannot find a solution that is working for me. I highlighted all of the pages in the Page panel and then went to Layout --> Margins and Columns and reduced my margins. The margins changed, but the text frames did not. I went to File --> Adjust Layout but nothing happened. Do I really have to manually adjust every text frame?
Once the text frame is attached to the margin - then you use Adjust Layout and the text frames adjust to the new margin positions.
Do not adjust your margins first.
You only need to use Adjust Layout and set your margins there only.
I thought my text frames already were attached to the margins when I changed them. How do I fix this now that I apparently did this in the wrong order?
There's a script I wrote that comes with InDesign called "Snap Margins to Text Frame". If you open the Community folder in the Scripts Panel in InDesign you should find it there.
Since your margins are no longer the same as your text frame, select a text frame on a right-hand page and run the script. Now all the margins will snap to the dimensions of that frame.
Now, resize that text frame to the size you want and run the script again. All the margins and all the text frames that were sitting on those margins will be resized to match the selected frame.
This is essentially the same as Adjust Layout, but it works more reliably in my opinion.
Well, that script successfully moved the margins back to the text frame size. Then I went to Layout --> Margins and set them to the desired size. As seen before, the text frames did not resize, so I manually resized that text frame to the margin, and ran the script again. Nothing happened. All my other text frames are still the smaller size and have not snapped to the new margin size.
When you ran the script the second time, there was no difference between the size of the text frame and the size of the margins, so nothing happened.
The first step you did was correct -- moving the margins back to the frame size.
The second step should have been simply: Select a text frame on a right-hand page. Change the size and position of that frame to whatever you need. Then run the script. The script itself will snap the margins throughout to the selected text frame, and readjust all the other frames as well.