Noob question about checkout page

[dakiriki]

Hi,people!
I am just starting my first VM website, only thing I am not able to figure out is on checkout page.
There is button with two arrows next to product that, what is for?
When clicked, does nothing, does it have some purpose?
At firs I was thinking that it is due to something I have done wrong, but seems to be same on demo store.
Thank you in advance.

P.S. : I know question may sound stupid, but I just started with VM.

[Maxim Pishnyak]

Your VM version and url?

[dakiriki]

My website is still on local server, but  VM is latest.
I have also created demo store with link provided on download page, and arrow button is not working also.
Here is image from demo store with arrows marked. When clicked, page refreshes and nothing happends.

[Maxim Pishnyak]

My website is still on local server, but  VM is latest.

There're a lot free web hosting services around us. Choose one of them to help us to give you a hand.

[dakiriki]

Sorry for this, but this is fastest solution, since it is not working there also.
I have never touched anything, and guess that since it is demo provided by you, should be working, right?
If you want I will give you user and pass also, but like said, I never touched anything.
https://darecomp.shops.virtuemart.com/

[Maxim Pishnyak]

There is button with two arrows next to product that, what is for?
When clicked, does nothing, does it have some purpose?

On posted by you url I can't reproduce your issue. What is your browser (its version)? Did you check your issue in another browser btw?

[dakiriki]

Thank you for yours help.
I have tested with : Chrome/Chromium, Opera,FF and IE9
Here is what I do:
1. Choose product, add it to cart
2. On checkout page I click on "update quantity in cart"
3. Page refreshes, but quantity stays same as before
Strange thing is that in message area I get this :

Product quantity successfully updated

Just like on image in previous post.

[Maxim Pishnyak]

Did you change amount of quantity before clicking button?

[dakiriki]

Well, I am noob, right? 
So it is used to calculate new sum after I change quantity?
Yes, when I change it first, and then click on button, I get updated fields.
Thank you so much for yours help, I will try not to ask such questions anymore.

[Maxim Pishnyak]

I disagree with your decision! Moderators need some fun time to time.

[dakiriki]

I feel so ashamed now. 
You can have yours fun, but with somebody else, I hope.
Thank you again.

[Maxim Pishnyak]

Any time.

[jenkinhill]

It is the International Symbol for synchronise!