The only way to control work buffer on the Android app is to reduce the allowed storage space use, or set the Min.spare storage high, what BOINC is not allowed to use. Mine is set to Max used storage, 20%. With about 3GB free, that works out at 0.6 GB, which gives me 3 to 4 units, 2 running, the rest waiting. With 10 days deadline, and runtime of about 6-10 hours per result, it varies, the tablet is enough time on charger each day to finish all tasks before deadline (unreliable, so the device never gets repairs with 3.5 day deadline).

Please make sure you have "Show advanced preferences and controls..." turned ON from preferences. Then "No new tasks" option will be available. It is off by default.

You must have a different version, no new tasks is under projects, click WCG then the 3 dots which bring up an ugly black text on dark blue menu. Selecting WCG below project should gives a more legible menu with more options including NNT.

Ah, the advanced under preferences also changes the project level menu. Pretty silly to not show NNT by default.

little mermaid, SekeRob and Halo Jones, thank you all for a solution to a problem that will not arise until I replace my iPhone with an android, Looking at the Galaxy 8+ for th large viewing screen. Probably by years end..