Here are the instructions I found on how to reset the Clear Blue Easy Fertility Monitor back to its default settings. (Like if you are borrowing a friend's monitor to use, you want to reset it to clear all her data from the machine so it can learn YOUR cycles.) I hope this helps.
1. Remove the plastic cap from one end of a clean-unused-test-stick and snap the cap onto the other end of stick. Inset the test stick into the test stick slot of the monitor. The beveled corner on the insertion end of the stick must face in toward the monitor. THE STICK MUST SNAP INTO PLACE TO PERFORM PROPERLY . The monitor should not be turned until step 2.
2. Press and hold the "M" button. Continue pressing the "M" button while turning the monitor on. NOTE: Do not take finger off the "m" button until these directions say to do so in STEP 5.
3. The screen will show the "remove the test stick" symbol (a flashing test stick with an arrow pointing right). Continue pressing "M".
4. Keep pressing the "M" button and in about 20 seconds, you will see a screen full of symbols. The screen will also display these symbols when you initially turn the monitor on for the FIRST time. This indicates the memory is now cleared of all prior data.
5. Remove the test stick first and then QUICKLY release your finger from the "M" button. The memory should now be cleared.
6. Your screen should display a flashing "M" and one or two dashes. If it does not, it will probably show a "1" and an "M" in a non-flashing mode. If so, you will need to repeat all steps of the process. This procedure may take several times before you successfully reset the unit to its “new” state.
7. Start using the monitor on CD 1 as per the instruction booklet.