我的联想 Flex 5 15 上只有一个操作系统 - Elementary OS 5（基于 Ubuntu 18.04 的众多发行版之一）。当我打开笔记本电脑时，Grub v. 2.02 启动菜单会出现，我有 30 秒的时间进行选择（例如，开始加载 Elementary 或 Setup）。
我想跳过此启动菜单并让 Elementary 默认启动。我尝试编辑/etc/默认/grub，但它没有改变任何东西。这是我的 /etc/default/grub 内容：
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'
GRUB_DEFAULT="elementary"
GRUB_HIDDEN_TIMEOUT="0"
GRUB_HIDDEN_TIMEOUT_QUIET="true"
#GRUB_TIMEOUT_STYLE="hidden"
GRUB_TIMEOUT="5"
GRUB_DISTRIBUTOR="`lsb_release -i -s 2> /dev/null || echo Debian`"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""
# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"
# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL="console"
# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE="640x480"
# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID="true"
# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"
# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"
GRUB_DISABLE_OS_PROBER="true"
我已经尝试通过 Grub Customizer 更改 grub 配置，但没有成功。以下是我更改的选项的屏幕截图：
