Will I use data when on wifi?

@mrlerch wrote:
In your iPhone, go to Settings, Cellular and scroll all the way to the bottom. There turn off Wifi Assist. That way when wifi is enabled, even when slow, cellular will not assist or take over.

Don't just turn it off. See what the usage is first!

Look at which program uses the most and then TURN THAT ONE OFF!

@Jimmy123.  @Gary L Is correct.  The problem is not with the cell service, which apparently is excellent. The problem is the cell service is far better than your wifi service.  Most apps that use large amounts of data have options within the app to limit to wifi only.  

You indicate you upgraded phones.  If you went from a slower old phone to a phone with a bigger, higher density screen, more ram, etc.  you went from economy car to a performance car.  This could be why you use more data.  When LTE phones came out data use doubled for many customers.  

At the same time the cost of data has been halved.

Uh, No I did not switch phones but I appreciate the assumption. It's the EXACT same phone and I actually quit playing online games on my phone which you would think would reduce usage, not increase it. The problem is that when I am connected to WIFI, it still uses my mobile data if it's faster. The only way to turn this is off is to turn off mobile data as told to me by an ATT rep on the phone today. Since the software "upgrades" my data usage has shot through the roof and I'm looking at other carriers because checking out facebook a couple of times a day and running spotify a few hours a week shouldn't equal 6.6 gigs a month of usage. I go into apps and turn them off and don't load my phone with heavy background usage because I know better. I have troubleshooted this and racked my brain for solutions... 

@Jimmy123. Which programs are using the most mobile data?

I can just turn it off, downgrade my plan and use my laptop at home when I want to internet. not like you need a big data plan to be a living human. 

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@Jimmy123.@. wrote:

I can just turn it off, downgrade my plan and use my laptop at home when I want to internet. not like you need a big data plan to be a living human. 

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Correct.  Or you could just figure out which program is using the most data....?

You can keep going in circles or look at your phone.  I have the feeling you have no idea how or where to look.  

Open settings, data/cellular usage and scroll down.   How much data does Spotify say it used?

How many hours a week?   My sons were listening to Spotify while working part time, 15 to 20 hours a week.  Spotify alone was 6.5 to 9 gigs a month.  Example below for iPhone and android.

Jeez, sorry I said anything. I still am reading a lot of assumptions being made. Yes, i understand where to look and what apps are using the most space. Recently, I have noticed a rise in my data usage while attempting to use less data. Whether this is from apps, a software update or ATT is something that I don't feel like pursuing anymore.

This forum has definitely reminded me that I don't need places like this. I was clarifying that an ATT rep told me that your mobile data usage can be used while connected to WIFI and the solution given to me is unacceptable. Sharing this in such a place can help other frustrated people understand that they aren't the only one. I don't feel the need to go down the rabbit hole to  tetris my phone and usage anymore. I don't appreciate being drilled as if this is "user error" anymore. 

If my solution is to uninstall apps, use less data, and search for cheaper options that may suite me better, that's my choice right?