terminal - Xterm*selectToClipboard doesn't work when put in Xresources -

i have problem xterm , can't figure out wrong:

i need enable option *selecttoclipboard in xterm able copy text in terminal.

to firstly tried "manually" start xterm option following command: xterm -xrm 'xterm*selecttoclipboard: true' work well.

then enable option each time xterm started put following line xterm*selecttoclipboard: true in ~/.xresources , used command xrdb -merge ~/.xresources update settings doesn't work: xterm starts option isn't enabled , can't copy text terminal whereas other options in xresources enabled , work fine.

does have idea of cause problem?

short answer: need add line bellow in /etc/x11/app-defaults/xterm file

*selecttoclipboard: true 

long answer: if @ man pages xterm(1):

man xterm  files    actual pathnames given may differ on system.  ...    /etc/x11/app-defaults/xterm         xterm default application resources.     /etc/x11/app-defaults/xterm-color         xterm color application resources.  if display supports color, use                   *customization: -color         in .xdefaults file automatically use resource file rather /etc/x11/app-defaults/xterm.  if not this, xterm uses compiled-in default resource settings colors. ... 

i did not find reference user configuration file set xterm application defaults, except xterm-color, don't think exists.