You should have 5 tabs in the BIOS.
Information> Configuration> Security> Boot Exit.

Arrow to "Boot"
Use the up and down arrows to select your usb device and make it the first device in the list.

None of the tabs say boot.
Main, Devices, advanced, power, security, startup, exit. Those are the tabs. I already said what's in startup. Under devices are USB setup and several others. If I select USB setup I see; USB Support and USB legacy support. Both say enabled

Am I indeed in the BIOS. The window I am in is labeled: Lenovo BIOS setup utility.

As mentioned I have different tabs. Under startup, inside the tab, if I go down to CSM the help message says: compatibility support module permit that loading of a traditional OS. Enable; to support non UEFI operation system. Disable: to support win10 64 bit and later UEFI AWARE OPERATION SYSTEM. when CSM enabled. secure boot will automatically set to disable.

I am wary of doing this but it seems that I should enable CSM. Then it can support non UEFI operation system. Is that what I want? I am not seeing what you described. The tabs are different for one thing. Is a BIOS setup utility different from just BIOS?

You might have to enable primary boot sequence, CSM in order to see the usb stick.
Try CSM and see if it will let you change the boot order of your devices.

The BIOS setup utility and the BIOS should be the same thing.

If enabling CSM is a problem you can always undue what you have done.

I just did that, enabled CSM. It started normally. This computer is conspiring to drive me crazy

I just found a real easy way to get into BIOS. On startup it will auto start to Mint unless I scroll down. At the bottom is setup. That is BIOS. I am going to set CSM TO enabled and see what happens.

I am replying to my own quote HA. So I am back at the GNU grub start page, where i can select win10, mint advanced options or system setup. Nothing seems changed.

If you can't change the boot order I don't see how you will be able to install Ubuntu.

How did you install Mint without changing the boot order?

Sad to say I don't remember exactly how I did it. I must have selected, somehow, for it to boot off the USB. I am probably just not seeing what should be obvious. The USB stick with Ubuntu is plugged into the machine. Perhaps its not plugged into the right USB socket?? I will try a different one and see if that makes any difference.

Ok-

Midnight is near and I'm close to going to bed.
Sorry I can't stay up much longer.

Good night. Sleep well. It did not make a difference which usb socket.

I am sure you are snozzing away right now. But I thought I'd share this find with you. I think I found how to change the boot order. I had to go to Lenovo support to find this: https://pcsupport.lenovo.com/us/en/solutions/HT104668
To make matter worse microsoft decided I have shut down and restarted my puter too many times and made me jump through hoops for an hour before I could get back into my machine.. ugg !! Oh.. I know, they are just trying to keep us safe. Once I get Ubuntu up and running I won't have to deal with Microsoft anymore, except occasionally to do stuff I can't on Ubuntu.
You have been very kind to give up some of your time to help me. I do appreciate it. However, I am disappointed that more people did not chime in with just the info I need. I get it that this is a volunteer operation. But if dummies like me can't make Linux work for us, that leaves a lot of folks stuck with MS Windows. I want to be clear I am not knocking any of you people that have tried to help me. Thank you one and all. It is probably all my fault anyway. Maybe I'm too dumb to own a computer??
Sucess- sort of. When Lenovo logo appears I repeatedly and rapidly pressed F12. I was then given the option to boot from USB stick. Unfortunately when tried to use wifi in the live USB, or whatever it's called, it said no network adapter is detected. I think it might work if I were to plug into an Ethernet cable, because instructions on the install window said to be sure and be online when you install so that wifi and other software can be downloaded. So maybe my whole problem is that I am not on a wired network. Oh well. Live and learn. Learn and forget.
I don't know if this is useful but I managed to pair up my smart phone with Ubuntu. Is it possible to transfer files or drivers that way? Text in the Bluetooth window on Ubuntu says: 'available for file transfers. transferred files are placed in the downloads folder'.
I could have a triple boot system- win10, mint, ubuntu. But that option requires a lot of time, because everything on the Mint partition has to be written to disc first. I am not willing to get rid of Mint yet. I still don't know if Ubuntu will work or need a driver for the wifi adapter. But Ubuntu is not saying it lacks a driver. It is saying it does not detect the wifi adapter in the machine. Ugg !!
I just discovered another way to get files into Mint or Ubuntu. You can save them in window and get to them from Mint or Ubuntu by doing this: 'https://askubuntu.com/questions/145992/ubuntu-doesnt-recognise-my-wireless-adapter#146058'
If nothing else this post is a record of my attempts and failures. That might be worthwhile info for others. Everything you need to know is on the internet. The trick is finding it- just like its a trick finding stuff on a computer. Knowing what, how and where to search is a good skill to have.