This is probably only true for Matlab version before Matlab 2019a
You could change it permanently if you have a copy of Matlab on your local machine (i.e. it’s not a server version Matlab).
Locate file: default_getDatatipText.m
in the directory:
\toolbox\matlab\graphics\@graphics\@datacursor
change the line defining number of display digits to higher:
DEFAULT_DIGITS = N; % Display N digits of x,y position as you wish
Save the update, quit the current Matlab instance, restart, done!