Can I change the Settings without doing a Full Reset?

Yes you can change any of the settings without the need to do a full reset.
Here is an example to change the Stride Length:

Press the MODE button until “STEP” is displayed
Press and hold the SET button to enter setup mode
The dispay will begin flashing
Press the SET button repeatedly until the display changes to Stride Length
Press RESET to increase the number, or MODE to decrease the number
Once you have selected the stride length you require do not press any more buttons and the pedometer will exit setup mode after approx 4 seconds.
These are the same steps for changing any of the settings:
Repeatedly press the SET button until the screen changes to the setting you wish to change and then use the RESET / MODE buttons to increase or decrease the values.