When you save a symbol the Origin is the point which
will sit on the end of your cursor as the symbol is inserted into a document.
The default location for the origin in new documents is 0,0 but this can
be changed using the page shown here or by using the Set Origin command.
If your origin lies outside the extents of the objects in your document and you use the document as a symbol, the origin will be ignored. What will happen instead is that the symbol will centre itself on the cursor as it is inserted. This is a safety precaution because it is conceivable that a symbol’s origin could be a very long way away from the objects that make that symbol up. If this was the case and the symbol inserted, at certain zooms you wouldn’t be able to see the addition of this new symbol - it would be way off the screen.
The 2 checkboxes in this page set the way in which co-ordinate values increase. By default all are checked which means that x values increase as you go right, y values increase as you go down.
