timing belt questions

i put in 1 timing belt and had a shop put 2 one. it acting like it slip teeth again. i run with no power. do you have to go back in and tight the lack after a while?

If the procedure is done correctly, there is no need opening it again to tighten. OF course, it need be properly symchronised . Review procedure here:
www.avigex.ca/kia/TimingBelt.zip
www.avigex.ca/kia/timingmarks.jpg
www.avigex.ca/kia/timingbelt_.jpg