By default the seed list added from Tools->Maintain Seed Data is set at the project level. To make the seed data global, i.e to be able to use it in all the projects, you will have to run the following query against the repository.
1. Go to Test Data->Test Data Repository SQL Window.
2. Run this query (the syntax given below is for a sql server repository)
update dbo.gtrep_reference_data set rd_proj_id = 0 where rd_ref_id = '<Seedlistname>';
Please let me know if the above helps
Thanks,
Aditi