thanks @adw it seems you did have this issue before 
so to confirm the solution is to add
XTerm*selectToClipboard:true
into default xterm configuration file ~/.Xdefaults
answer has been given previously here indeed
I did try to search here before but didn’t match the rights keywords to find the solution.
Hopefully this topic will index more keywords to bring here future users stuck the same scenario…
Thanks @adw 
for your thoroughly help !!