Greetings....

I have two torrent files That refuse To seed & Their status was ( Standby seed ), How can I make them return to seeding mode ???

open more slots?
Settings > Transfers > General > Queuing > Upload slots +++++

or to really get serious, select the torrent you want to be seeded, then ... Right click on it, go to Seeding then check  Constant Seeding
That will open an additional fixed slot that will always be active for this torrent.

Thanks Mr.Bugmagnet Your second Solution Really helped >>> problem Resolved Thanks Again