Hi, Mostyn.
ming.yuan@live.com is the right place, thanks for your Donation.
1 Option/Index Manager/Update Now
This means syncing files to the index.
2 Sync A Folder
This means syncing files in a spec folder to the index.
3 re-index
This means deleting all index data first and rebuilding the index database.
4 If you just want to only indexing a specific folder.
Go to Option/Index Manager/File type, Ctrl+A select all file types, and click edit to set your folder.
Best
Yuan