texlive2025, TeXstudio, reinstallation

Good evening, from Greg Bennett

I am trying to get TeXstudio 4.9.0 to work with texlive2025 under linux 
mint 22.2

Both are new installs.

As a check I created ~/gtest,tex:
\documentclass{amsart}
\begin{document}
$$
x = y + \sin z
$$
\end{document}

 From a terminal in my home directory I ran
pdflatex gtest.tex
which told me it was using Version 3,141592653-2,6-1.40.28 (TeX Live 
2025) (preloaded format=pdflatex)
and ran to completion with the expected gtest.pdf. This suggests that 
the TeXlive installation was found.

I deleted that ,pdf, fired up TeXstudio, opened gtest.tex, hit Build & 
View from its Tools menu
to get an immediate dialog:

Could not start Build & View:PdfLatex:
pdflatex -synctex=1 -interaction=nonstopmode "gtest".tex

In the Messages tab:
(green text) Process started: pdflatex -synctex=1 
-interaction=nonstopmode "gtest".tex
(black text) kpathsea: Running mktexfmt pdflatex.fmt mktexfmt: No such 
file or directory
Process exited with error(s)

which mktexfmt   returns /usr/local/texlive/2025/bin/x86_64-linux/mktexfmt
the directory part of that value is the first element in $PATH as 
instructed by the texlive install.

I asked the developer/'owner' of TeXstudio who replied:

This is a question about proper latex installation on linux.
I would suggest to ask tex.stackexchange.com or similar.

It seems that there are path difficulties I can't (yet) solve.

My install followed www.tug.org/texlive/quickinstall.html  with the 
--paper=letter option,
and installed 4938 files before setting things up, with no complaints in 
my install-tl.log
(I have a fairly fast connection - the file themselves took 17:32 ins)

If I need to reinstall texlive, do I need to remove all the earlier 
install ?

Is there a -full option to make sure I get everything ?

Perhaps there are other options or environment variables I need to get a 
'proper' installation.
Both $TEXMFHOME and $TEXINPUTS are undefined.

Any and all advice/assistance will be much appreciated

Cheers
Greg Bennett