I am 28 yr male my total testosterone is 247 the range is (240-900),online they say 240 is level for 80yr old. is my value really low? please advise

It is probably fine: As you see there is a broad range of T levels in healthy men and being at the low end of normal should not cause any symptoms such as low libido or energy. However if you knew your T a year ago was 500 that decrease might indicate a problem. If you have symptoms c/w low T, have your doctor recheck your level in 6-12 months