It seems that after I did the update to 3.3.1 of audacity, there is a lag in audio in my headset when I record in audacity. I’m running it on a Lenovo laptop, Windows 10 Home. I have a Focusrite Scarlett solo interface. What do I need to change in settings for there to not be a lag in the audio in the headset as I record? Please help!
If only all the questions were this easy. 
Simply plug your headset into your Focusrite.
Once the audio enters the computer it gets buffered and there will always be a delay. You can change this delay a little bit by manipulating the size of the buffer, but you can never get it to 0. See: Audio Settings Preferences - Audacity Manual
From the Focusrite manual:
The Scarlett Solo is fitted with a “Direct Monitoring” option, which overcomes this problem. Setting the front panel DIRECT MONITOR switch to ON will route your input signals directly to the Scarlett Solo’s headphone and main monitor outputs. This enables you to hear yourself with zero latency – i.e., in “real time” – along with the computer playback. Your inputs will be summed to mono, so both mic and instrument will appear in the centre of the stereo image. Note that the input signals to your computer are not affected in any way by the use of Direct Monitor.