how do i update software

Go to Settings/General/Software Update. Note that not all models can be updated beyond a certain version:

• Any model 6S or newer (including original SE and 2nd edition): You can update to iOS 14.x
• iPhone 5S or 6: You cannot update to iOS 14; you can update only to iOS 12.5.1
• iPhone 5: You can update only to 10.3.4
• iPhone 5C: You can update only to 10.3.3
• iPhone 4S: You can update only to 9.3.6
• iPhone 4: You can update only to 7.1.2

Realize you may not be able to update. Read this link for the easiest way to find out what your device can run: "Update your iPhone, iPad, or iPod touch" --> https://support.apple.com/HT204204

- When you try to update you will only be given one update selection which will be the highest available iOS version supported by your device. If it says the device is up to date and you need a higher OS version you will have to buy newer equipment.