B747 pilot reported a malfunctioning window caused cabin pressurization issues during cruise. Flight returned to departure airport.

Narrative

In cruise the noise from the repaired" right side window became increasingly worse and intrusive. The noise increased in volume with increases in altitude. Ear and sinus discomfort became noticeable Cabin altitude was rapidly changing +/- 300 feetCabin Rate of Change observed rapidly cycling from -800 to +1600 feet per minute without stabilisingA review of the Aircraft Log book highlighted multiple entries over the previous week regarding the replacement of the right side window with repeated entries of excessive and intrusive noise.The Captain contacted the company via SATPHONE and conversed with Dispatch and Maintenance. We are directed to "turn around and return to ZZZ"ATC were informed and we were directed to climb to FL390 and turn left "direct to waypoint ZZZZZ". The ATC clearance was then "Direct ZZZZZ RXXX ZZZZZ1 Direct ZZZ". The diversion was commenced after passing waypoint "ZZZZZ2".Physiological discomfort became more prevalent as the flight progressed.A gentle descent of 500fpm was commenced for a stable and continuous descent into ZZZ. ATC assisted throughout.The approach and landing were completed with multiple EICAS (Engine Indicating and Crew Alerting System) messages upon touchdown which disappeared shortly after appearing. These included "Right Outflow Valve" and "Auto Pressurisation Controller" but as PF my attention was outside the aircraft.After landing all four pilots remarked about having headaches; sinus pain and " feeling generally odd".Cause: Possibly inadequate maintenance standards and quality control.Suggestions: Greater weight placed upon repeated entries by aircrew."