Hello, I have a hybrid Mongoose bike, orginally had the straight
handlebar for aggressive riding, but I prefer to sit as straight as
possible so I switched to the curved handlebar and adjusted it so it
was as upright as possible, it is an adjustable stem

Now I stick to street riding, but I do get aggressive attacking hills,
I like to stand up at different portions of the ride, eventually I
noticed the handlebar moving slightly back and forth, a little loose,
me being the novice rider I thought it was no big deal until one day it
collapsed forward, if I wasn't going slow I would have flipped over

So I brought it back to the bike shop and they tightened it up, I'm
sure this problem will happen again, I'm scared it will just collapse
forward without any warning next time, so what are my solutions

Do I have to go back to the agressive straight handlebar and put it at
a neutral position and not so high up forcing me to lean over more on
the ride, or do they sell a straight handlebar with some sort of an
added attachment that allows you to sit up straight or stand up and
ride aggressive if you want to switch during the ride

basically do they make a combination handlebar, sorry for the rambling
message, thanks for your help