The fact that our attitudes change poses well-known challenges for attitude-sensitive wellbeing theories. Suppose that in the past you favoured your adventurous youthful life more than the quiet and unassuming life you expected to live as an old person; now when you look back you favour your current life more than your youthful past life. Which period of your life is better for you? More generally, how can we find a stable attitude-sensitive standard of wellbeing, if the standard is in part defined in terms of unstable attitudes? In this paper, I introduce an 'attitudinal matrix' framework that will help us clear up the problems posed by changing attitudes across time. In particular, it will help us see what is at stake, which principles that can or cannot be combined, and what might be the best solution. I defend a very plausible candidate constraint on a solution to the challenge of changing attitudes, which I call 'diagonalism'. It is argued that among the three main forms of substantive attitude-sensitive wellbeing theories - the attitude-version, the object-version, and the satisfaction-version - it is the satisfaction-version that can both satisfy diagonalism and provide the best account of temporal and lifetime wellbeing.