Multiple Bugs In Indesign v16

Hi! I've been having some trouble with Indesign. 

-I've accidentaly installed both the v16 and the 15.3 versions. whenever I open a file, it randomly opens with either version. For example: I've created a file in version v16. I open again, but it automatically opens in v15.3, and says that I should download the newer version of Indesign to work on my file

-I've tried removing the v15.3 of my computer, but everytime I try to uninstall it, a pop up message tells me to close the application and try again, and I don't even have indesign open in the moment.

-Another thing that's happening: If i click a specific indesign file, indesign doesn't start. I have to open the indesign app, and select the file from my computer. Sometimes, even when I click the indesign app itself nothing happens.

How can I fix this?

thanks!