weak pull-up resistor

This depends on the target device you have. I am not shure if all targets do support weak pull ups.

but if the target supports this is very easy with the assignment editor.

if your top level is a schematic then just highlight the pin then locate it inside the assignment editor.

now you should see your pin selected with at least the pin location assign to it.

now clic an empty assignment name field and press "w" the possible weak pull up resistor should be available press enter and go to the next field on the right an enable it with YES press enter.

thats it. now recompile.

have fun.