Can see that version go to mobile settings go to about and you can see that page name:windows phone model,Nokia Lumia 625 or another model software:windows phone 8 or 8.1.
If you have windows 8 you don't worry about that you can upgrade directly to Windows too,no need to upgrade Windows to 8.1 first then upgrade to Windows 10.You can directly upgrade to Windows 8 or 8.1 to windows 10.
So let's start,connect your phone to WIFI or Mobile date then click the search icon on the store then search for windows inside it is the official app from windows.
Windows insider or check out the link below to directly download just click windows, insider.After that, you can see this the windows insider application details provides registered insiders the ability to receive pre-release os update on their phones direct about more information and becoming a windows insider visit http://insider.windows.com.
You just click install,let's take it sample its just 1mb you can see app installed.So now let's view the app open the app then click the,get preview build.
You have seen two options insider slow and insider fast. I will explain you,what is the different between insider slow and insider fast.
First, I will read you insider slow,Windows 10 pre-release build for Windows 10 but you will get them a little after inside who install to receive a fast update this could mean that more solutions are available for issues that insider slow.
You will get the pre-release a kind of slow.I because the fasters get it first and they test it and they fix it the bugs,then you will get the os updates and the second option insider fast windows 10 you will get pre-release update build for windows 10 head of everyone else.
This means you will see new things sooner,but there may be a fewer solution available for the issue.
You will get the updates fast but it has some bugs before they release the os.I mean they release the technical preview updates one by one and you will get the faster and without fixing bugs.
Windows phone 8.1 this update can help,make your phone work better.You,ok we just install this update by clicking install and its restarts your phone.Its shows the logo of the phone but it still shows windows 8,you need to do something its migrating your data will 0 to 21.
Your phone ready to windows 10 for the phone.We'll handle this for if you leave your phone plugged into a power and we'll notify you when the update is ready.if you'd like to start the process now and simply launch windows insider app then selects your preview to build again.
This will reboot your phone and initiate the update to windows 10 Technical preview.That is the next step go to insider app it will instruct you to and click the get preview build.Upgrade you phone to windows 10.Select insider fast clicks to go and click accept.
Click install and it restarting and its windows 10.Now you can check your phone version and you can show the menu different.let's go to system and it shown the about click the about and software windows 10 mobile insider.