Ctrl+A does not select all in URL bar in Chrome and Firefox

Selecting all text in URL by Ctrl+A doesn't work anymore. Now it brings the cursor to the front.

Try the following (not guaranteed to cover your problem but it's a possibility):

Open your Dash and type in "Tweak" to get to the Tweak Tool (Note that this is not the same as "Ubuntu Tweak") - alternatively, in a console type gnome-tweak-tool (if it is not currently installed, type sudo apt-get install gnome-tweak-tool to install it)

Go to the Keyboard & Mouse > Emacs input (formerly Theme section > Gtk+ Keybinding Theme). If this is set to "Emacs", then Ctrl+A will essentially act as if it were the Home key. If this is the case, change the option to "Default" to restore the usual settings.

Alternatively, in Firefox and Google Chrome you can use the shortcut Ctrl+L to select the entire title bar.

Ctrl+A usually goes to the front of the string in the CLI. You should check the Keyboard shortcuts by clicking the gear icon in the top right of your screen:

and then clicking: System Settings→Keyboard

Note: On my PC, CTRL+A has the normal behaviour!