To pause downloading all torrents, go to the torrent list view, tap on the menu button (three dots) in upper-right corner of the screen in portrait (vertical) mode, then tap Pause All. Note that some Samsung devices will have the menu button in the lower right corner of the phone, not on the actual screen. To pause downloading one or more torrents, tap on the toggle next to the torrents you would like to pause.
Tip: once you’ve selected one torrent, you can select all of the rest by tapping on the button that appears on the upper-right corner.  It looks like a box with multiple dots around it.

To pause seeding on all torrents, tap on the menu button (three dots) in upper corner of the screen in portrait (vertical) mode from the torrent list view.  Tap Pause All’.  Note that some Samsung devices will have the menu button in the lower right corner of the phone, not on the actual screen.  To pause seeding on one or more torrents.  Tap on the toggle next to the torrents you would like to pause. 

Tip: once you’ve selected one torrent, you can select all of the rest by tapping on the button that appears on the upper-right corner.  It looks like a box with with multiple dots around it.