How can I make Unity 2D the default session at start-up? [duplicate]

Solution 1:

when logging in there is a symbol in the top right of the box (usually a ubuntu logo unless using something else) click on the logo and then click ubuntu 2D , if you dont change this , you will always log into unity 2d

Solution 2:

To set the default for all users, you can use

sudo /usr/lib/lightdm/lightdm-set-defaults -s ubuntu-2d

or you can edit the file /etc/lightdm/lightdm.conf directly. See this documented version.

Per-user settings are stored in either $HOME/.dmrc or in /var/lib/AccountsService/users/$USER . According to this post, the latter file may overwrite your .dmrc.