apps reinstalling after each reboot

Hi,

I have the new MacBook Pro and the newest MacOs.

Unfortunately after each reboot there are some aps that need reinstallation (like Mozilla, hangouts). When I click on the object for the first time after reboot, reinstallation from disc starts. It's not taking long but it is annoying. Do you have an idea how to fix it? On my older device it's never happening.

I know from the previous answer that "Most downloaded apps come in a disk image, ".dmg" file or compressed in a ".zip" archive. The apps must be installed from their delivery media." But I'm not really sure what does this mean to install an app from delivery media? Could you give me an example basing on installing hangouts of mentioned firefox?

Thanks for your any help on that.

Cheers,

Yaffi