5.0 lollipop - How do I manage users on my HTC One with Android 5?

I have HTC One (M7) with Android 5.0.2 (the unlocked ROM 7.17.1540.7 from HTC website). I want to set up several user accounts.

I've found two documented ways to do it:

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  The one concerns Nexus and consists of opening the settings and “ under 'Device,' touch[ing] Users.” There is no “Device” group, the only groups I have are “Wireless & networks”, “Personal” and “Phone”. There is no “Users” in any of those three groups.

  
  


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  The other one (also here) seems to apply to any Android 5 device, and asserts the following:

  
  
  

  
  

  Pull down your notification shade, and you'll see your user icon

  
  

  
  

  There is no user icon there. At the very top, there is the name of the operator. Below, I can see the time and date at the very left, and a settings icon at the right. If I expand quick settings panel, at the left of settings icon a new icon appears, allowing to go to “Edit Quick Settings.”

  
  

In settings, there is “Accounts & sync” element, but it looks like it handles online accounts used by different applications, making it possible, for example, to associate my Google account with the device. This is how “Add an account” looks like:

What am I doing wrong? How can I create users?

Answer

This might not be a solution¹ for your device and situation, but explaining the issue and possible help others working around it:

When it was "invented" with 4.2-jelly-bean, the multi-user feature was intended for tablets only. One of the reasons behind that was e.g. what to do with incoming calls and SMSs: to what user should those belong? Does the (one-and-only) SIM belong to the primary user? So what shall we do when (one of) the secondary user(s) is currently logged-in and working?

"It is not at all clear how it should work on a phone, specifically with respect to SMS and phone calls," writes Dan Morrill, Google Engineer and a regular on the popular /r/Android subreddit

^{Source: AndroidPolice}

With 5.0-lollipop this seems to have slightly changed, as you've pointed out in a comment on your question:

Even a smartphone […] now offers multiple user accounts.

[…] When Google released Android 4.2 it included multiple user accounts for tablets; however, smartphone users were left in the cold. This has now changed.

^{Source: CNet}

And the official pages even state, without explicitly restricting that to any manufacturer:

You can create up to 4 users on a phone and 8 users on a tablet.

Still, not all manufacturers decided to "jump that train". Some simply "patched out" the corresponding menu entries from the settings app (in which case you can use e.g. Activity Launcher to reveal and use it), others removed that functionality altogether (seemingly the case with your device). In the latter case, there's nothing you can do without rooting your device.¹

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^{1: solutions in your case require the device to be rooted; then follow up Arielle's answer}