Newbie question around desktop UI testing

Hi!  Welcome to TestComplete!

One of the things to understand about how TestComplete works is that, at the core of the tool, is a feature called NameMapping which is how TestComplete identifies objects for interaction.  NameMapping uses a combination of object hierarchy and object properties to identify the specific object.

So, one thing that happens frequently is that object properties, many times, have a dynamic nature where the values of those properties change due to many factors.  There are ways of mitigating this such as selecting different, more static properties for identification, using wildcards in the object identification properties, etc.

Basically, when you recorded your test, the objects were mapped automatically with properties and property values at the time of recording.  When you play back the test, if there were such dynamic properties, the objects are not identified because those properties changed since the test was recorded.  

This is one of the "dangers" of record/playback method of creating automated tests.  It really is a powerful way of getting started... but it is a rare application that works 100% well with record playback.  I would say at LEAST 90% of the time, after you record something, you will need to go back and make multiple adjustments to object mapping and in playback timing.

For Object Mapping, I would start with reading https://support.smartbear.com/testcomplete/docs/testing-with/object-identification/name-mapping/overview.html and all the various literature on that.

For Timing, I would read the topics under https://support.smartbear.com/testcomplete/docs/app-objects/common-tasks/index.html

Please feel free to continue to ask specific questions here.  We're happy to help newbies. :)