Like most text editors, our editor uses Enter to add a paragraph break (double space). To single space, use Shift+Enter. This is also true with Word. If you have created a document in Word and plan to copy it into Ministry Sync, make sure you use Shfit+Enter for a line break (single space) and Enter for a paragraph break (double space). This video has more information for line spacing in Word.
Additionally, some templates, like the Invitation email, have tables to create columns. These columns may affect alignment and spacing. Please contact Support if you need help customizing your templates.