<emergency> terrible update error

This update has severe errors.
One of them is erasing randomly -phenomenon.  it's terrible for techers who use writing tools. 
When we erase the writings using the eraser (writing tools), other contents is erased together randomly.
It has occured persistently and we have suffered from your poor update.
I want to stop paying you.
Whenever you update, several bugs have existed but you didn't care much and didn't respond quickly.
Please check and revise bugs which I mentioned.