The text boxes must be exactly in size and shape, and fill the page.
Here’s an example
sheet size: A4, height = 29,7 cm, width = 21 cm
margins: left = 2,00 cm, right = 1,00 cm, above = 2,80 cm, below = 2,90 cm
Instead of using text fields, I would use frames. These can be reached via Insert> Frame> Frame .... They are better to work with.
At frame, tab “Type”: Anchoring: At the side, Size: width = 9,00 cm, Height = 8.00 cm,
Position: Horizontal - From Left by 2 cm to Full Page, Vertical: Horizontal - 2.8 cm from top to full page;
Klick OK
In the other tabs “Options”, “Circulation”, “Hyperlink”, “Border”, “Area”, “Transparency”, “Columns”, “Macro”, there are still many setting possibilities.
You can re-insert the frame with Ctrl + C and Ctrl + V (several times). Then adjust the position in the “Type” tab.
You can of course use other dimensions for page and margins, then you should adjust the frame dimensions.