Jagged font display in Indesign

I am working on a MacBook Pro with an additional monitor.

Although the display is great for continuous tone images (Photoshop) and it's fine for text in email and Word, when I work in Indesign, the fonts look jagged. Has anyone else had this problem, and found a solution?

Here is my system set up:

MacBook Pro (15” 2017), 2.8 GHz Intel Core i7, 16 GB memory, Graphics Radeon Pro 555 2048 MB, Intel HD Graphics 630 1536 MB

Mac OS Sierra 10.12.6

The connection from monitor by Thunderbolt to LETSCOM (USB) to USBC

The monitor is LG 34UB88-P 21:9 Ultrawide

I am working in Indesign CC 2018.