For the furnace crash the game crashes half of the time when removing fuel from the furnace. The sign crash when typing in words then when your done the game sometimes crashes. These all also lead to the reset glitch were the game makes anything you made disappear.
MCPE-7928
Furnace crash and sign crash again!
Resolved
Duplicate
0
Thank you for your report.
However, your ticket has been resolved as a duplicate.
This issue has been linked to the original bugreport: MCPE-4879. You can find or add further information on that report.
Please search before reporting any bugs, as it's likely that one exists already.