The position of the glossary in the list represents its priority (the glossary at the top of the list is the one having the top priority).
To change the glossary priority
1.Select the glossary
2.Click on the 
Priority Up or 
Priority Down button in the ribbon to change the glossary priority
The priority of the glossary is changed
How priority affects phrase execution
Autocorrect glossaries
If two terms share the same Misspelled text value, the element present in the higher priority glossary is used.
Example:
Glossary Autocorrect 1 (with priority 1) containing
(c) -> copyright
and
Glossary Autocorrect 2 (with priority 2) containing
(c) -> copyright 2011
typing:
(c) [SPACE] will expand to:
copyright
(uses the top priority glossary)
Phrase glossaries
If two phrases share the same abbreviation, the phrase belonging to the higher priority glossary will be shown first.