iCloud storage upgrade

Use a web browser and sign with Apple ID and password in appleid.apple.com , in country section first click on edit you can change country ( click on drop down arrow and select the desired country and click done to save ) .

for changing mobile number , again click on edit first add your new number , then click on cross sign in front of old number to delete , then click on done .

The prefix code of country will be stay if you purchased a sim from Dubai and used their cellular services after that returned back to your hometown , then you have to use your mobile number of the country that you belong , see the article https://support.apple.com/en-in/HT201389

See the articles https://support.apple.com/en-us/HT201266

https://support.apple.com/en-in/HT202631

Are you getting an error message?

Buy more iCloud storage - Apple Support

I am not able to change pre fix +971 (UAE mobile code) nor country nor even currency

I tried on Mac but still not able to change pre fix +971 and country/region nor currency.

I am trying to upgrade my icloud storage on my iphone but it will not let me?????

Same here buddy.