New version of configuration file /etc/default/grub is available, but the version installed currently has been locally modified

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt-get update
sudo apt update
sudo apt upgrade

then this screen appeared and it says

A new version (/tmp/grub.5gRinQVE9u) of configuration file /etc/default/grub is available, but the version installed currently has been locally modified.
What do you want to do about modified configuration file grub?
install the package maintainer's version
keep the local version currently installed
show the differences between the versions
show a side-by-side difference between the versions
show a 3-way difference between available versions
do a 3-way merge between available versions
start a new shell to examine the situation

how do I fix this?

thank you!!

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