When creating a new world, and changing the rules in the Game Rules menu, if you hit Done after changing some, then go back into the Game Rules menu, the mouse-over tool-tip where it says "Default:" will now show the current setting, rather than the original default.
Linked issues
is duplicated by 4
MC-230431
Tooltip default value displays the currently applied value on the Game Rule screen
Resolved
MC-239485
Default game rule sets to yours
Resolved
MC-295851
Hover tooltips for game rules on the world creation Edit Game Rules screen change based on what you previously set them to
Resolved
MC-296061
When recreating a world, the listed default values for gamerules mimic any changes you have made
Resolved
This is a duplicate of MC-180587, but I think it was closed in error