To see how changes you have made to a proposal template will transform in your proposals, first create a proposal (you can just select any random services)..
..ensure you have selected the proposal template you have been making changes to in your admin area.
Scroll down, hit get calculation and then choose complete proposal.
Don't worry about filling out any client or staff details, just scroll past all of the fields until you find the preview proposal tab and open this up.
Here, you can preview the proposal to view the changes you have made.
You can use the refresh icon in the top right of the PDF preview to preview any further changes you make.
>> How to edit proposal templates and the proposal PDF