To reduce line height & section spacing, on the Finish up & Preview page, please click Adjustments, and you'll see the options to change the Line height and Sections spacing:
Make sure that it's set to the lowest value to have small spaces between lines and sections.
You can also disable the Section Divider (horizontal line icon) option to further decrease the space between sections.
For further assistance, please visit our User Guide, use the support chat on the right side of the screen, or email us at support@rezi.io.