According to the manual, the arrows are gear change recommendations (like in a new car) - never seen the up arrow and occasionally see the down flicker she I'm cycling fine so there is definitely something not right with the SW on that.i think the arrows are for the batt usage up gaining more miles and down for going to fast lol.
should be in the manual tho
tbh my 6 quid thing from halfords does a better job, even keeps time pmsl