Hi, so for ages I was frustrated because I couldn't seem to use the paint tool with full functionality, until I opened a new file in extended which had the full functionality of paint tool (with the three icons below the other icons at the top). Is there a way to tell whether the file I am using it normal or extended?

First, you can switch back and forth between Extended and “normal” with the menu entry in View | New themes. 

The last mode used in LDD is stored in the file when you save it so that LDD goes to the “correct” mode when you load the file.
You can open LXF files as ZIP files and then open the IMAGE100.LXFML file inside, the mode is in the Brand tag.  That may be a bit too technical though….

Thanks, view-themes does the trick. The one which is not bold must necessarily be what the file currently is. I have another question regarding wheels and hubs, but I'll start a new topic.