Lines and surfaces not visible unless selected

hi, actually I am currently using rhino 6 on mac , and a few of the lines and surfaces are not visible unless selected, and some of these surfaces are visible partially. Is there a easy solution for this?

Hi - please run the Rhino SystemInfo command and copy-paste the result here.

Rhino 6 SR22 2020-1-28 (Public Build, 6.22.20028.13212, Git hash:master @ 379871ece695dc096e83826f08b429db8ca2e7f5)
License type: Evaluation, build 2020-01-28
License details: Stand-Alone
Expires on: 2020-05-15

Apple Intel 64-bit macOS Version 10.15.3 (Build 19D76) (Physical RAM: 16Gb)
Mac Model Identifier: MacBookPro14,3
Machine name: Akhila’s MacBook Pro
Language: en-IN (MacOS default)

AMD Radeon Pro 555 OpenGL Engine (OpenGL ver:4.1 ATI-3.5.5)

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On

Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: Height

Vendor Name: ATI Technologies Inc.
Render version: 4.1
Shading Language: 4.10
Maximum Texture size: 16384 x 16384
Z-Buffer depth: n/a
Maximum Viewport size: 16384 x 16384
Total Video Memory: 2 GB
Graphics: Radeon Pro 555
Displays: Color LCD (258dpi 2x)

Graphics processors
Intel HD Graphics 630 (1536 MB)
Radeon Pro 555 (2 GB)
Color LCD (1680 x 1050)

USB devices
MOSART Semi.: 2.4G Wireless Mouse
Apple Inc.: Apple T1 Controller

Bluetooth devices

Third party plugins

Rhino plugins
/Applications/ “RhinoCycles” 6.22.20028.13212
/Applications/ “Snapshots” 6.22.20028.1002
/Applications/ “Grasshopper” 6.22.20028.13212
/Applications/ “PanelingTools” 6.22.20028.1002
/Applications/ “Commands” 6.22.20028.13212
/Applications/ “RDK_EtoUI” 6.22.20028.13212
/Applications/ “AutoCAD file export : export_ACAD” 6.22.20028.1002
/Applications/ “Displacement” 6.22.20028.1002
/Applications/ “ACIS Export” 6.22.20028.1002
/Applications/ “IronPython” 6.22.20028.13212
/Applications/ “Rhino Render” 6.22.20028.1002
/Applications/ “AnimationTools” 6.22.20028.1002
/Applications/ “Renderer Development Kit” 6.22.20028.1002

One possibility is that the lines are set too thin. In the display settings under OBJECT make the CURVE WIDTH and ISOCURVE WIDTH larger than 1 (say 3).