The main.tex file in my project is the one to be opened in editor view in order to successfully compile the pdf-document. It has several child-files like e.g. content.tex where I write the actual thesis text.
Every time I want to compile the document in order to view the changes I have to change the editor-file to main.tex. Otherwise the process ends with errors.
I already tried the Ctrl+0 base file setting, but it did not show any changes.
The LaTeX project is based on a template provided by my university and though has to stay untouched in regards of the project structure itself (why so ever...).
I managed to do as I strived to. Don't know whether I'd just been too clumsy or if it relates to the problems I faced during the \input{...} integration, but if anyone wonders how to do so too:
It in fact has been the way I already tried - set the main-document to master-document.
Nevertheless I switched to use TexStudio meanwhile. Thank you for your response @Gowachin