...
Customer the TM is connected to;
Language combination;
Specify if the change has to be performed only for the TM related to a specific project(s) (provide its name or ID(s) - please, click here for help) or all of the projects under this particular customer and language combination.
...
Before raising a ticket, however, please, make sure you are well familiarized with what TM reindexing actually is and what details to include in the ticket form from the relevant article: Reindex of translation memory.