Claire
Try this out:-
1. Select 'songs' view.
2. Press CMD A (select all songs) - OR navigate to edit menu->select all.
3. Then 2-finger click the highlighted cells to get the pop-up window.
4. Select 'check selection' to check all songs.
Now all songs can be played.
With the album view you have three icons next to the album title:-
A. The standard symbol for play.
B. The middle symbol is probably shuffle (random play the album tracks) but I never use it.
C. The right symbol (>) which pulls up a drop down menu of options.
You can double click on a track to play it OR by selecting the icon (>) to pull up the drop down menu for that track.
Regards
Mark