Log File and Simple recovery mode

I quickly came to the point: It is say when we set the recovery mode in ‘simple’, any existed record on ‘LogFile’ overwrite despite I did this setting, with update specific field at any time, the new record added to ‘LogFile’ instead of replace on previous record related to field.

for example when I change particular field value from 25 to 34 and then from 34 to 66, two record added to 'LogFile'.

Why is this happen? Because this records storage method related to ‘Full’ recovery mode that include file size skyrocketing.

Thanks a lot.