BleepingComputer.com: Regional and Language Options Set To Default

I need to reset my Regional Language setting to default, . .

I see that this can be done by clicking advanced tab in the Regional and Language options

and checking the bottom box; Default user accounts, . . .

however this also says;

You choose to apply settings to the default user profile.

These changes will affect the logon screen and all user accounts.
Some system services may require you to restart your computer
before the changes will take effect.

Please tell me what effects will occur, . . I think I need to do this because on certain occasions I am inadvertently activating something that causes some language abnormalities to occur, when typing English, etc.