JasperReports Server uses Mondrian properties that are set by Mondrian engine. For example, JasperReports Server v4.7 and v5.0 engine version is mondrian-184.108.40.20661. To override those properties /WEB-INF/classes/mondrian.properties file is used.
Some of the properties are updated by default. If you don't see any of the properties that are available in UI (Server Settings/OLAP settings) simply add them to the file and restart JasperReports Server, for example:
mondrian.rolap.queryTimeout=30 mondrian.util.memoryMonitor.enable=true mondrian.util.memoryMonitor.percentage.threshold=180