In order to change the odds type in the mobile version, click on the "Sports A-Z" at the bottom of your screen. In case you are using PC version, click on the cog on the right of ‘Betslip’ and ‘My Bets’ on the right hand side of the screen.
Once you click on it, this will open up a small menu with ‘Odds Type’ showing at the top, which is where you can choose between three formats for the display of your odds - Decimal, Fractional or American.