Sounds like you have 'Automatic update' switched on for your Normal style --
this means that any formatting change you make becomes part of the style and
is then applied to all other paragraphs of the same style.
Select Format > Style. Select Normal from the style list. Click Modify.
Clear the 'Automatically Update' check box.
Don said:
When I bold the first characters of the first line of my document, the
whole document turns bold. I've tried everything that I know to stop this
action. What is going on?