Have to reinstall lol every update

I'm sick and tired of doing this process all the time. Pls fix this riot. When there is an update it says update this but it doesn't update so I click on lol again and it says an older version of lol has been installed pls update. I'm confused. Pls help riot this has been happening for some months and I thought it was fine but it just keeps on getting on my nerves. And then I have to uninstall then install lol in order for it to update. Pls fix this riot.