I have deleted old, closed accounts, and hundreds of old transactions and the file size does not get smaller. What do I have to do to shrink the QDF file?
Use the file copy process on the File menu.
When you delete transactions or accounts, Quicken does not reduce the file's size, it just makes the newly made space available to use for future transactions/accounts without making the file bigger.
The file copy process makes a new file using only the space it needs.
Note that the copy file feature will also remove all online connections, so you will have to reconnect them in the new data file.