Canonical Search Consol

Hello, please note that I am not very techy person. Please explain your answers in very simple terms and steps.

I replaced my Yoast software with Rank Math to improve my SEO. Rank Math suggested that I change the name of my URL (Permalink) to match that of the title and meta description. I followed the instruction.
Here’s an example:
Old URL: https://farhatlectures.com/cost-volume-profit-analysis-cma-exam-cpa-exam-bec/
New URL: http://farhatlectures.com/cost-volume-profit-analysis/

What happened as a result? When I try to do a “URL inspection” on Google Search Console

I get the following message for the old URL:
Coverage: Duplicate, submitted URL not selected as canonical

I get the following message for the new URL:
URL not in property
Inspect a URL in the currently selected property or switch properties

Can you please help me resolve this issue. It seems that Yoast had a place to just put the new URL to fix this issue. I cannot find a solution on Rank Math. Thank You