Chrome opens everytime, even not the default browser

In System Preferences/General is Chrome or Safari chosen in the drop down menu?

It might be easiest to delete then reinstall chrome. Have you tried restarting your computer then seeing if the same behavior is happening? As I remember when you first opened Chrome it asks if you want it as the default browser.

f you happen to be conversant with the Terminal app and the macOS command prompt, there’s a command that rebuilds the LaunchServices database. Type it (or copy and paste the following) in at the command prompt, press Return, then wait for a few minutes until the command prompt reappears:

/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user

When the command prompt reappears, type:

killall Finder

then press Return to relaunch Finder and begin using the rebuilt LaunchServices database

macOS file associations are useful for determining which apps can read, write, open or edit specific file types. These tips provide a way to further control file associations on your Mac.

https://blog.macsales.com/47149-quick-tip-managing-macos-file-associations

I've been using a macbook air for few months. I'll suggest you to use safari as a default browser. I found that a post which describes chrome uses a lot of ram to make things stable. Safari does the same thing but in other manner consuming less RAM. I'll suggest you to use safari and uninstall or restrict chrome background processes. I was also using the chrome but after noticing the RAM consumption I switched back to safari.

Nice to see new helpers in here! :)