A few of the functionalities of the online player can be changed through the options panel. To load the options panel press the "Options" button.
The following settings are available:
Ticking this box will cause the player to mark the conflicts in red. Note that the player does not know the solution of the puzzle. If you enter a wrong number that does not conflict with other numbers the mistake will not be highligted, but if you enter a number that already exists in the same box or in the same row or in the same column, both conflicting numbers, except for givens, will be marked in red.
Pressing the automatic pencil marks button fills all empty cells with all possible values based on the cells that have already been filled. Leave this box checked if you want to use this functionality.
Some players do not like to see the ticking timer while they are solving the puzzle. Uncheck this box if you do not want to see the timer. The timer can also be hidden during play by pressing the "Hide timer" button.
The small and big selectors provide two different ways to enter numbers and pencil marks in the grid. See entering numbers for a more complete description of each input type.
The coordinates are used to identify individual cells in the grid. They are useful if you like to take notes while solving the puzzle. Leave this box checked if you use the coordinates system.
Some sudoku books and websites use letters to identify the rows in the grid, others use numbers. Select your preference.
After you have made your selection press "Done" to close the options panel.