The Copy Format tool can be found on your Content tab. Its purpose is to allow you to copy the format from any column or field and paste it to another (for example, text or number).
Apply a format to a column or field (right-click and select "Column Format in Output").
Click on the Copy Format button: once if you only need to paste the format to a single column or field, or twice if you need to paste the format to multiple columns or fields.
Hover your cursor over the column/field you want to apply the format to. You should see a little paintbrush. Left-click your mouse to apply the format. Repeat this step with any remaining columns/fields you need to apply the format to.
When you're done, click the Copy Format button again to deselect it.