How od I upgrade my Premium account to Next and retain current Todoist tasks?
I use it on Windows 8,1 Pro, and Android (Galaxy Note 2 and 8.0)
It's account based, just log out of all browsers, apps, and log back in, it should grab new information. Android needs to be updated, it shoud be in your Play Store updates.
If that does not help, clear the cache for your brower.