The PM3365A is an early digital scope, essentially an analog scope with a digital capture/storage unit - so the sampling is rather slow and digital features are not as fancy as today's designs. It also uses numerical 'dials' for most of the standard knobs, making it a bit unintuitive for someone used to a traditional analog scope (and hard to read the settings, as the LCDs are not lit).
Analog bandwidth is 100MHz, but sampling speed is 100Ms/s giving a useful digital bandwidth of only about 10 - 20Mhz.
Some hints for use may be found in the Reference manual (pdf) - a peculiar substitute for a proper service manual that manages to provide no useful service information.
Or the User manual if the link continues to work.