Introduce the operation method:

First, the new vertical screen resolution.

Open the love clip on the computer, and in the "New" box that pops up, change the "video size" to the portrait screen, such as:1080 *1920 (1080p portrait screen).

Then import the horizontal video into the software, and the effect is shown as follows:

Second, add a background picture to cover the black border.

Double-click the video preview area on the right under the Add Map panel to select the appropriate background picture in the pop-up box and adjust the size, position and duration.

I hope I can help you!