I dare say I’m missing something obvious here but wonder if anybody can point me in the right direction please

Basically I have the Sony WH-1000XM3 Bluetooth headphones along with various Apple devices.

The headphones pair with each device properly, my question centres around connecting to the various devices at different times - nb this is not about being connected to multiple devices at the same time.

I connect to say the iPad by turning the headphones on, if the iPad was the last device used the headphones connect automatically to it no problem. Before switching off I make sure the iPad is set back to use the iPad speakers and disconnects from the headphones.

Next day I want to connect them to my iPhone, so I switch the headphones on again but they automatically connect to the last used device, on this example the iPad again.

The problem comes when then getting them to connect to the iPhone. At the moment I can only do that by going to iPhone Bluetooth settings and telling it to forget the headphones. I then have to go into pairing mode on the headphones and repair with the iPhone and then I can use it with the iPhone as desired. Ive tried simply pressing the connect button in the iPhone Bluetooth settings, it says connected but the little headphone icon doesn’t appear and the audio still comes from the iPhone speaker.

If I want to use them next with the iPad I have to go through that process again etc etc.

This is a bit of a faff every time I use a different device and I’m hoping there is a way of making the headphones connect to the device I want to use them on without going through the forget/ re-pair process?