Just press the red button to start a new recording.

Other than that, there are some other convenience ways to start a new recording:

1.Quick action on the app icon

If your iPhone (6s, 7, 8) support 3D touch, deep press on the app icon, then quick actions will be shown, select “Record” to start a new recording quickly.

2.Shortcut

Since iOS 12, shortcut can be created to start new recording in Recorder Plus.

To do so, first tap the red button in Recorder Plus to start a new recording, this will register this action to iOS, and this register action only need to be done once.

Then download “Shortcuts” app if it is not on your iPhone.

Then you can just download the shortcut to start new recording

Or you can create the shortcut on your own by following Apple’s official guide:

Create a new shortcut

In the action search box, just input “start recording”, you will see the Recorder Plus action, add it!

When you created the shortcut, you can add it to home screen or add it to Siri.

Then you can start a new recording just by tapping an icon on home screen or even by Siri.

Detail information on how to use shortcuts:

Apple’s shortcuts user guide

Other information maybe you need to know:

Incoming call or alarm clock would interrupt the recording. But the recording would be resumed automatically when the incoming call or alarm clock ends.

The audio hardware couldn’t carry different Apps at the same time. Therefore, please don’t open other Apps when you are recording. If there are sounds from other Apps, the recording would stop and will not resume  automatically.

Reference:

Continue recording on an exist recording