Help with config of AP One Mini

Network newbee in need of help. First of all, I have the AP One Mini HW2 connected to my SOHO Mk3 and it is working. Both are at the latest Firmware versions. I think the AP is configured as DHCP, since it got an IP address from the SOHO. I would like to configure it as a static IP to the SOHO. I know where to set the static IP in the SOHO, but where do I set the AP to use a static IP? I see under the System tab in Operating Mode, Router Mode, Bridge Mode, and Bridge Mode without LAN IP address. What do these mean? Out of the box the AP is set to Bridge Mode. Is this what I need, or do I need Router Mode? I thought that the SOHO assigned the IP with its DHCP. Also do I need to be concerned with the WAN configuration on the AP? I assume that the SOHO takes care of that. Sorry for so many questions, I am new at this and trying to understand it better. The manual seems to assume that the reader is familiar with networking.

Since the AP is in bridge mode it acts more like a transparent switch.
On the clients tab of the soho click on the tag icon on the far right of the ap’s ip.
This will add it as a dhcp reservation to the soho.
Then whenever the ap or soho reports it will have the same ip.