You will find the “Always accept better odds” option under My Account > Preferences > Betting Preferences.
When you have enabled (ticked) the “Always accept better odds” feature, it means that if your selected line changes in your favor with greater payout result, the bet slip automatically accepts your wager.
If you do not wish to use this feature and would like to receive a line change notification message, please untick the check box next to “Always accept better odds” to turn it off.
When you have disabled (unticked) the “Always accept better odds” feature, it means that if your selected line changes, the bet slip will always notify you before accepting your wager.