The day of the week

My watch tells me the day of the week and the current time.  It can deal with something about the tides, too, but I don't need that and I don't use it.  When the month of March began, it began to tell the day of week incorrectly.  The last time, it was wrong, I went to a local jewelry shop and a woman got the watch corrected quickly.  But this time, two different women said they didn't know how to fix it.  One of them advised me to use the numbers on the back of the watch, find the right manual and follow instructions to correct the watch.  I had no faith that such a procedure would work but I was wrong.  

I had time last night and used the numbers to find the appropriate instructions, followed them and now my watch says it is Thursday!