Linux why do i have to run commands instead of running the bash file

In order to run an executable file, I need to run all the commands in the below bash file first, so I just put those commands in the bash file and run the bash file first, but running the bash file doesn't work, I have to run the 4 commands one by one in the terminal and then run my executable file in the same terminal , why do I have to do this, why running the bash file doesn't acheive the same as running the commands one by one:

#!/bin/bash
export LD_LIBRARY_PATH=/repo/$USER/ncmain/out/rcpi/ITC_CXA11466/x86/lib
export ITC_RUNDIR_PATH=/local/scratch/$USER/itc/
export ITC_INSTANCE_NAME=itc_$USER
/local/scratch/ehhozzo/RCS_ROOT/software/itcworld