Any suggestions, please?

Audacity 1.2.6 was the final version of the 1.x series, and has been obsolete for many years.
The current version of Audacity is 2.2.2 and is available via the Audacity website:

It’s very common for commercial CDs to be very loud due to the loudness war.
The loudest that it is possible to get a recording without distorting it at all, is to Normalize to 0 dB. To get louder than that requires dynamic range compression, which may be achieved with compressors, limiters or distortion effects.