Try my advice on your iPad (deleting emails), maybe it's also possible with your iOS version.
If you have to update, make sure iTunes on your computer is up to date.
Dave's screenshot was not taken on the iPad, it's from a computer. As soon as iTunes (computer) is updated, connect your iPad to the PC via USB cable. iTunes should open by itself. If it doesn't, open it and wait for your iPad to appear in iTunes. It's possible that you get a popup, asking whether or not you trust this computer - on your iPad. If so, select "Trust".
Then it will be possible to backup the iPad in iTunes on your PC, so you don't lose data on your iPad when you update it.
After backing up, update your iPad, also using iTunes on your PC.
Hope that helps.
If you have to update, make sure iTunes on your computer is up to date.
Dave's screenshot was not taken on the iPad, it's from a computer. As soon as iTunes (computer) is updated, connect your iPad to the PC via USB cable. iTunes should open by itself. If it doesn't, open it and wait for your iPad to appear in iTunes. It's possible that you get a popup, asking whether or not you trust this computer - on your iPad. If so, select "Trust".
Then it will be possible to backup the iPad in iTunes on your PC, so you don't lose data on your iPad when you update it.
After backing up, update your iPad, also using iTunes on your PC.
Hope that helps.