I'm learning how to use Realband on Windows 10 to record live instruments and vocals on to tracks. I'm using an HP Notebook model 15-db0048ca and a new Focusrite Scarlett Solo V3 interface unit, the one with the new "AIR" button on it. Previously I was using a Fostex MR-8 recorder machine to do recording, then transfering the recorded WAV files into my Windows 10 laptop and importing them into the free 16 track KRISTAL audio engine application, so I wasn't actually recording ON my laptop. The BIAB/REALBAND tutorials that I looked at didn't really give me the very basic startup information I needed to do that kind of recording.
=======================
I found an experienced user who helped get me started. He set up my drivers as below:
FOCUSRITE SCARLETT SOLO DRIVER SET UP IN REALBAND...
Options > Preferences > 2 Audio tab ...
Audio Driver Type: select MME (this driver seemed to work best for me, (started with little probs)
Drivers: Click on the "Drivers" box to see the available selections.
Under the Audio Input Drivers, select "Analogue 1 + 2 (Focusrite Usb A..."
Under the Audio Output Drivers, I selected my laptop's own "Speaker/Headphone (Realtek High..."
=======================
Once the above settings were put into place, I was able to record through my Focusrite Scarlett Solo V3 interface.
I put my RealBand app into the "Tracks" view by clicking on the "Tracks" icon in the "ALL TRACKS" section at the top of the RealBand window; then arming a track by clicking on one of the track numbers along the left side of the tracks; then clicking on the round red "Record" record button along the bottom of the RealBand window. Basic, basic stuff that the tutorials I watched didn't tell me. My mentor also showed me how to move a recorded track to the left or right on the time line by selecting/high lighting it then, while hold down the control (ctrl) key, dragging the recorded section to where I wanted it. He also reminded me that I could shrink or increase the viewed track timeline by hovering the cursor over the tracks and rolling my mouse wheel each way. I think I finally can get started using RealBand with that simple lesson. :-)

A few observations.....

Why are you using MME? With the focusrite, you should be using ASIO.

Second observation. Yeah I get it that you can slide tracks right and left on the track timeline but the question is why do you need to do that?

The only reason I ever need to slide a track one way or the other is generally a vocal track and it's to create a sort of doubled sound by putting the tracks out of sync by a few milliseconds. So...If you are having to do this to be sure everything is properly synced, you have a problem that should not exist. It goes back most likely, to the choice of the MME driver.

Next observation. You should be using the Focusrite for BOTH the input and the output. Run a pair of powered speakers from the Focusrite. Using the laptop's Realtek sound card could be part of the reason you are having issues. In this music recording thing we do, you really only need to use ONE sound card for both in and out. When you introduce two sound cards, you do not.... let me repeat that... you do not have clock sync between them. That will certainly cause issues with the music not staying in sync properly. Reassign the outputs to the focusrite.... they should be available to you, and with external speakers connected, see if that isn't a better solution for you.

What Guitarhacker said - choose ASIO, and make sure you're using the Focusrite for both in and out. If ASIO doesn't work properly, try opening the ASIO control panel and increase the buffer size bit by bit until it works properly. If it still doesn't work, try upgrading your driver from Focusrite.

MME is an older driver type - it has much higher compatibility and is more stable, but has a lot of latency. WAS or Windows Audio is newer and lower latency, but somewhat less compatible. ASIO generally has the lowest latency, but has the downside of requiring a specialized driver, and only one music app can access the ASIO driver at any given time.

I'd also opt for Focusrite ASIO drivers (like above suggestions) in RB. That way the drivers are what the hardware was designed to work with.
If I try to use MME with the Focusrite it seems to get angry sometimes.

Then again, there's the old saying; if it ain't broke don't go trying to fix it!

Thanks for your response. I'm so new to this that I pretty well have to learn every little thing from a scratch.

We all started there