TCMD's tab-system uses many registry entries which are version-specific. for example, in a key like "HKEY_CURRENT_USER\Software\JP Software\Take Command 18.0". Any customizations there will not apply to an upgraded version. Depending on where you made your registry settings, and how you use them, a new version might [not] use them.
Beyond that, TCMD.INI is of importance. Figure out where yours is with the command "echo %_ininame". If it's in TCMD's install directory or %programdata then it's in a version-specific place and should be copied to the new install directory. If it's in %localappdata it's not version specific. In either case, uninstalling v18 and/or installing v23 should not disturb it and also in either case it will have to be edited via the OPTION dialog, at least to change TCMD's "comspec" (to the new TCC) and the locations of any files for which there are new locations (e.g., TCSTART.BTM and TCEXIT.BTM which can also be copied from the old installation).