Special Note: Saving documents along with a copy for Saved Templates for future importing to create New Estimates is a Premium (Paid) Subscription feature. For more information on the Basic (Free) Version versus Premium (Paid) Subscription features please go here.
Saving a document just for the Estimate or Invoice you are working on is accomplished by selecting the Save icon. In order to save the document for the job you are working on, and for future reuse simply select the Save as Template as shown below.
Upon selecting the Save as Template, am option to save to the Default Templates Folder or a SubFolder appears similar to as follows below.
Learn more about Templates and Template Folders here.
You then type in the name you wish to call the reusable document and then hit the save as demonstrated below.
If you wish to see the above saved Template then you need to go to Templates feature in the Presets section and it would appear similar to the following.
Then the next time you have a new job that requires a document similar to one that you have saved here, you will simply create the new document by importing from templates by following the instructions as shown here.